Issue mirrored from https://github.com/slime/slime/issues/413

My slime just stopped responding and I just got this in my REPL:

```
Help! 11 nested errors. SB-KERNEL:*MAXIMUM-ERROR-DEPTH* exceeded.
Backtrace for: #<SB-THREAD:THREAD "auto-flush-thread" RUNNING {10025AFDA3}>
0: (GET-INTERNAL-REAL-TIME)
1: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
2: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
3: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
4: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
5: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
6: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002335E0B}>)
7: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002335E0B}>)
8: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070> #<unavailable argument>)
9: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
10: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
11: (ERROR TYPE-ERROR :DATUM -475929070 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
12: ("OBJECT-NOT-TYPE-ERROR" -475929070 (UNSIGNED-BYTE 62))
13: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF44C2DC0) #<unavailable argument>)
14: ("foreign function: call_into_lisp")
15: ("foreign function: funcall2")
16: ("foreign function: interrupt_internal_error")
17: ("foreign function: handle_trap")
18: ("foreign function: #x414773")
19: (GET-INTERNAL-REAL-TIME)
20: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
21: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
22: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
23: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
24: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
25: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002334ECB}>)
26: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002334ECB}>)
27: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070> #<unavailable argument>)
28: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
29: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
30: (ERROR TYPE-ERROR :DATUM -475929070 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
31: ("OBJECT-NOT-TYPE-ERROR" -475929070 (UNSIGNED-BYTE 62))
32: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF44C3A80) #<unavailable argument>)
33: ("foreign function: call_into_lisp")
34: ("foreign function: funcall2")
35: ("foreign function: interrupt_internal_error")
36: ("foreign function: handle_trap")
37: ("foreign function: #x414773")
38: (GET-INTERNAL-REAL-TIME)
39: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
40: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
41: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
42: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
43: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
44: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002333FBB}>)
45: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002333FBB}>)
46: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070> #<unavailable argument>)
47: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
48: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
49: (ERROR TYPE-ERROR :DATUM -475929070 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
50: ("OBJECT-NOT-TYPE-ERROR" -475929070 (UNSIGNED-BYTE 62))
51: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF44C4740) #<unavailable argument>)
52: ("foreign function: call_into_lisp")
53: ("foreign function: funcall2")
54: ("foreign function: interrupt_internal_error")
55: ("foreign function: handle_trap")
56: ("foreign function: #x414773")
57: (GET-INTERNAL-REAL-TIME)
58: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
59: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
60: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
61: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
62: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
63: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {10023330DB}>)
64: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {10023330DB}>)
65: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070> #<unavailable argument>)
66: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
67: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
68: (ERROR TYPE-ERROR :DATUM -475929070 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
69: ("OBJECT-NOT-TYPE-ERROR" -475929070 (UNSIGNED-BYTE 62))
70: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF44C5400) #<unavailable argument>)
71: ("foreign function: call_into_lisp")
72: ("foreign function: funcall2")
73: ("foreign function: interrupt_internal_error")
74: ("foreign function: handle_trap")
75: ("foreign function: #x414773")
76: (GET-INTERNAL-REAL-TIME)
77: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
78: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
79: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
80: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929071>)
81: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:INVOKE-SLIME-DEBUGGER) {10023320BB}>)
82: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:INVOKE-SLIME-DEBUGGER) {10023320BB}>)
```

And in the `*inferior-lisp*` buffer:

```
Help! 11 nested errors. SB-KERNEL:*MAXIMUM-ERROR-DEPTH* exceeded.
Backtrace for: #<SB-THREAD:THREAD "auto-flush-thread" RUNNING {10025AFDA3}>
0: (GET-INTERNAL-REAL-TIME)
1: (SB-SYS:DECODE-TIMEOUT NIL)
;  ..
2: (SB-THREAD:GRAB-MUTEX #<SB-THREAD:MUTEX "hash-table lock" (free)> :WAITP T :TIMEOUT NIL)
3: ((FLET #:WITHOUT-INTERRUPTS-BODY-425 :IN SB-THREAD::CALL-WITH-RECURSIVE-SYSTEM-LOCK))
4: (SB-THREAD::CALL-WITH-RECURSIVE-SYSTEM-LOCK #<CLOSURE (FLET SB-THREAD::WITH-RECURSIVE-SYSTEM-LOCK-THUNK :IN SB-DI::MAKE-COMPILED-DEBUG-FUN) {7FFFF44C164B}> #<SB-THREAD:MUTEX "hash-table lock" (free)>)
5: (SB-DI::MAKE-COMPILED-DEBUG-FUN #S(SB-C::COMPILED-DEBUG-FUN :NAME GET-INTERNAL-REAL-TIME :KIND NIL :VARS #() :BLOCKS NIL :TLF-NUMBER 94 :FORM-NUMBER 50 :ARGUMENTS :MINIMAL :RETURNS :STANDARD :START-PC 135 :ELSEWHERE-PC 1742 :CLOSURE-SAVE NIL :BSP-SAVE NIL) #<code object [3] GET-INTERNAL-REAL-TIME, "DEFUN" {21BB202F}>)
6: (SB-DI::COMPUTE-CALLING-FRAME #.(SB-SYS:INT-SAP #X7FFFF44C6800) #.(SB-SYS:INT-SAP #X7FFFF79C90C0) #<SB-DI::COMPILED-FRAME "foreign function: #x414773"> NIL)
7: (SB-DI:FRAME-DOWN #<SB-DI::COMPILED-FRAME "foreign function: #x414773">)
8: (SB-DEBUG::MAP-BACKTRACE #<CLOSURE (LAMBDA (SB-DEBUG::FRAME) :IN PRINT-BACKTRACE) {10024404AB}> :START 0 :FROM #<SB-DI::COMPILED-FRAME GET-INTERNAL-REAL-TIME, interrupted> :COUNT 1000)
9: ((FLET #:THUNK61 :IN PRINT-BACKTRACE))
10: ((LAMBDA NIL :IN SB-DEBUG::FUNCALL-WITH-DEBUG-IO-SYNTAX))
11: (SB-IMPL::CALL-WITH-SANE-IO-SYNTAX #<CLOSURE (LAMBDA NIL :IN SB-DEBUG::FUNCALL-WITH-DEBUG-IO-SYNTAX) {100233727B}>)
12: (SB-IMPL::%WITH-STANDARD-IO-SYNTAX #<CLOSURE (FLET #:THUNK :IN SB-DEBUG::FUNCALL-WITH-DEBUG-IO-SYNTAX) {7FFFF44C195B}>)
13: (SB-DEBUG::FUNCALL-WITH-DEBUG-IO-SYNTAX #<CLOSURE (FLET #:THUNK61 :IN PRINT-BACKTRACE) {7FFFF44C1A0B}>)
14: (PRINT-BACKTRACE :STREAM #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>> :START 0 :FROM :DEBUGGER-FRAME :COUNT NIL :PRINT-THREAD T :PRINT-FRAME-SOURCE NIL :METHOD-FRAME-STYLE NIL :EMERGENCY-BEST-EFFORT T)
15: ((FLET SB-IMPL::TRY-TO-INVOKE-DEBUGGER :IN SB-IMPL::ERROR-ERROR))
16: ((FLET #:THUNK :IN SB-IMPL::ERROR-ERROR))
17: (SB-IMPL::%WITH-STANDARD-IO-SYNTAX #<CLOSURE (FLET #:THUNK :IN SB-IMPL::ERROR-ERROR) {7FFFF44C1CDB}>)
18: (SB-IMPL::ERROR-ERROR "Help! " 11 " nested errors. " "SB-KERNEL:*MAXIMUM-ERROR-DEPTH* exceeded.")
19: (ERROR TYPE-ERROR :DATUM -475929070 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
20: ("OBJECT-NOT-TYPE-ERROR" -475929070 (UNSIGNED-BYTE 62))
21: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF44C2100) #<unavailable argument>)
22: ("foreign function: call_into_lisp")
23: ("foreign function: funcall2")
24: ("foreign function: interrupt_internal_error")
25: ("foreign function: handle_trap")
26: ("foreign function: #x414773")
27: (GET-INTERNAL-REAL-TIME)
28: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
29: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
30: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
31: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
32: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929070>)
33: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002335E0B}>)
34: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002335E0B}>)Help! ERROR-ERROR is 3 levels deep. Will try to THROW this thread to the toplevel.
Help! 11 nested errors. SB-KERNEL:*MAXIMUM-ERROR-DEPTH* exceeded.
Backtrace for: #<SB-THREAD:THREAD "Swank Sentinel" RUNNING {10021A3183}>
0: (GET-INTERNAL-REAL-TIME)
1: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
2: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
3: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
4: ((FLET SB-IMPL::TRY-TO-INVOKE-DEBUGGER :IN SB-IMPL::ERROR-ERROR))
5: ((FLET #:THUNK :IN SB-IMPL::ERROR-ERROR))
6: (SB-IMPL::%WITH-STANDARD-IO-SYNTAX #<CLOSURE (FLET #:THUNK :IN SB-IMPL::ERROR-ERROR) {7FFFF5EA961B}>)
7: (SB-IMPL::ERROR-ERROR "Help! " 11 " nested errors. " "SB-KERNEL:*MAXIMUM-ERROR-DEPTH* exceeded.")
8: (ERROR TYPE-ERROR :DATUM -475929051 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
9: ("OBJECT-NOT-TYPE-ERROR" -475929051 (UNSIGNED-BYTE 62))
10: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF5EA9A40) #<unavailable argument>)
11: ("foreign function: call_into_lisp")
12: ("foreign function: funcall2")
13: ("foreign function: interrupt_internal_error")
14: ("foreign function: handle_trap")
15: ("foreign function: #x414773")
16: (GET-INTERNAL-REAL-TIME)
17: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
18: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
19: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
20: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
21: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
22: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CD0D8B}>)
23: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CD0D8B}>)
24: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051> #<unavailable argument>)
25: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
26: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
27: (ERROR TYPE-ERROR :DATUM -475929051 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
28: ("OBJECT-NOT-TYPE-ERROR" -475929051 (UNSIGNED-BYTE 62))
29: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF5EAA700) #<unavailable argument>)
30: ("foreign function: call_into_lisp")
31: ("foreign function: funcall2")
32: ("foreign function: interrupt_internal_error")
33: ("foreign function: handle_trap")
34: ("foreign function: #x414773")
35: (GET-INTERNAL-REAL-TIME)
36: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
37: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
38: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
39: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
40: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
41: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCFE3B}>)
42: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCFE3B}>)
43: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051> #<unavailable argument>)
44: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
45: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929051>)
46: (ERROR TYPE-ERROR :DATUM -475929051 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
47: ("OBJECT-NOT-TYPE-ERROR" -475929051 (UNSIGNED-BYTE 62))
48: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF5EAB3C0) #<unavailable argument>)
49: ("foreign function: call_into_lisp")
50: ("foreign function: funcall2")
51: ("foreign function: interrupt_internal_error")
52: ("foreign function: handle_trap")
53: ("foreign function: #x414773")
54: (GET-INTERNAL-REAL-TIME)
55: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
56: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
57: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
58: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
59: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
60: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCEF2B}>)
61: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCEF2B}>)
62: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052> #<unavailable argument>)
63: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
64: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
65: (ERROR TYPE-ERROR :DATUM -475929052 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
66: ("OBJECT-NOT-TYPE-ERROR" -475929052 (UNSIGNED-BYTE 62))
67: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF5EAC080) #<unavailable argument>)
68: ("foreign function: call_into_lisp")
69: ("foreign function: funcall2")
70: ("foreign function: interrupt_internal_error")
71: ("foreign function: handle_trap")
72: ("foreign function: #x414773")
73: (GET-INTERNAL-REAL-TIME)
74: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
75: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
76: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
77: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
78: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
79: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCE04B}>)
80: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCE04B}>)
81: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052> #<unavailable argument>)
82: (SB-DEBUG::RUN-HOOK *DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
83: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
84: (ERROR TYPE-ERROR :DATUM -475929052 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
85: ("OBJECT-NOT-TYPE-ERROR" -475929052 (UNSIGNED-BYTE 62))
86: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF5EACD40) #<unavailable argument>)
87: ("foreign function: call_into_lisp")
88: ("foreign function: funcall2")
89: ("foreign function: interrupt_internal_error")
90: ("foreign function: handle_trap")
91: ("foreign function: #x414773")
92: (GET-INTERNAL-REAL-TIME)
93: ((:METHOD STREAM-FORCE-OUTPUT :AROUND (SWANK/GRAY::SLIME-OUTPUT-STREAM)) #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) [fast-method]
94: (FORCE-OUTPUT #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>)
95: (FORCE-OUTPUT #<TWO-WAY-STREAM :INPUT-STREAM #<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}> :OUTPUT-STREAM #<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>>)
96: (SWANK::DEBUG-IN-EMACS #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
97: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:INVOKE-SLIME-DEBUGGER) {1002CCD02B}>)
98: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:INVOKE-SLIME-DEBUGGER) {1002CCD02B}>)
99: (SWANK::CALL-WITH-BINDINGS ((*STANDARD-INPUT* . #1=#<SWANK/GRAY::SLIME-INPUT-STREAM {10024A78F3}>) (*STANDARD-OUTPUT* . #2=#<SWANK/GRAY::SLIME-OUTPUT-STREAM {1002592293}>) (*TRACE-OUTPUT* . #2#) (*ERROR-OUTPUT* . #2#) (*DEBUG-IO* . #3=#<TWO-WAY-STREAM :INPUT-STREAM #1# :OUTPUT-STREAM #2#>) (*QUERY-IO* . #3#) (*TERMINAL-IO* . #3#)) #<CLOSURE (LAMBDA NIL :IN SWANK:INVOKE-SLIME-DEBUGGER) {1002CCD04B}>)
100: (SWANK:INVOKE-SLIME-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
101: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCCFEB}>)
102: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/emiherd/.emacs.d/elpa/develop/slime-20171106.1331/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<CLOSURE (LAMBDA NIL :IN SWANK:SWANK-DEBUGGER-HOOK) {1002CCCFEB}>)
103: (SWANK:SWANK-DEBUGGER-HOOK #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052> #<unavailable argument>)
104: (SB-DEBUG::RUN-HOOK *INVOKE-DEBUGGER-HOOK* #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
105: (INVOKE-DEBUGGER #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929052>)
106: (ERROR TYPE-ERROR :DATUM -475929052 :EXPECTED-TYPE (UNSIGNED-BYTE 62))
107: ("OBJECT-NOT-TYPE-ERROR" -475929052 (UNSIGNED-BYTE 62))
108: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #X7FFFF5EADB80) #<unavailable argument>)
109: ("foreign function: call_into_lisp")
110: ("foreign function: funcall2")
111: ("foreign function: interrupt_internal_error")
112: ("foreign function: handle_trap")
113: ("foreign function: #x414773")
114: (GET-INTERNAL-REAL-TIME)
115: (SB-C::MAKE-SOURCE-INFO :START-TIME NIL :START-REAL-TIME NIL :FILE-INFO #<SB-C::FILE-INFO LISP> :STREAM NIL :LAST-DEFN-SOURCE-LOC NIL :PARENT NIL)
116: ((LAMBDA NIL :IN SB-C::ACTUALLY-COMPILE))
117: ((FLET SB-C::WITH-IT :IN SB-C::%WITH-COMPILATION-UNIT))
118: (SB-C::ACTUALLY-COMPILE NIL (LAMBDA NIL (LAMBDA (SB-PCL::|.P0.|) (DECLARE (OPTIMIZE (SPEED 3) (SAFETY 0) (INHIBIT-WARNINGS 3))) (BLOCK NIL (WHEN (SB-KERNEL:LAYOUT-INVALID #1=#<SB-KERNEL:LAYOUT for SWANK/GRAY::SLIME-OUTPUT-STREAM {20460703}>) (SB-PCL::INSTALL-INITIAL-CONSTRUCTOR #<SB-PCL::CTOR SWANK/GRAY::SLIME-OUTPUT-STREAM #>) (RETURN #)) (LET (# #) (SETF # #1#) (SETF # SB-PCL::.SLOTS.) (LET NIL # #) SB-PCL::.INSTANCE.)))) #<NULL-LEXENV> NIL NIL NIL)
119: (SB-C:COMPILE-IN-LEXENV NIL (LAMBDA NIL (LAMBDA (SB-PCL::|.P0.|) (DECLARE (OPTIMIZE (SPEED 3) (SAFETY 0) (INHIBIT-WARNINGS 3))) (BLOCK NIL (WHEN (SB-KERNEL:LAYOUT-INVALID #1=#<SB-KERNEL:LAYOUT for SWANK/GRAY::SLIME-OUTPUT-STREAM {20460703}>) (SB-PCL::INSTALL-INITIAL-CONSTRUCTOR #<SB-PCL::CTOR SWANK/GRAY::SLIME-OUTPUT-STREAM #>) (RETURN #)) (LET (# #) (SETF # #1#) (SETF # SB-PCL::.SLOTS.) (LET NIL # #) SB-PCL::.INSTANCE.)))) #<NULL-LEXENV> NIL NIL NIL)
120: (COMPILE NIL (LAMBDA NIL (LAMBDA (SB-PCL::|.P0.|) (DECLARE (OPTIMIZE (SPEED 3) (SAFETY 0) (INHIBIT-WARNINGS 3))) (BLOCK NIL (WHEN (SB-KERNEL:LAYOUT-INVALID #1=#<SB-KERNEL:LAYOUT for SWANK/GRAY::SLIME-OUTPUT-STREAM {20460703}>) (SB-PCL::INSTALL-INITIAL-CONSTRUCTOR #<SB-PCL::CTOR SWANK/GRAY::SLIME-OUTPUT-STREAM #>) (RETURN #)) (LET (# #) (SETF # #1#) (SETF # SB-PCL::.SLOTS.) (LET NIL # #) SB-PCL::.INSTANCE.)))))
121: ((FLET SB-THREAD::WITH-RECURSIVE-LOCK-THUNK :IN SB-PCL::INSTALL-OPTIMIZED-CONSTRUCTOR))
122: ((FLET #:WITHOUT-INTERRUPTS-BODY-387 :IN SB-THREAD::CALL-WITH-RECURSIVE-LOCK))
123: (SB-THREAD::CALL-WITH-RECURSIVE-LOCK #<CLOSURE (FLET SB-THREAD::WITH-RECURSIVE-LOCK-THUNK :IN SB-PCL::INSTALL-OPTIMIZED-CONSTRUCTOR) {7FFFF5EAE6BB}> #<SB-THREAD:MUTEX "World Lock" owner: #<SB-THREAD:THREAD "Swank Sentinel" RUNNING {10021A3183}>> T NIL)
124: (SB-PCL::INSTALL-OPTIMIZED-CONSTRUCTOR #<SB-PCL::CTOR SWANK/GRAY::SLIME-OUTPUT-STREAM (:OUTPUT-FN SB-PCL::|.P0.|)>)
125: ((LAMBDA (&REST SB-PCL::ARGS) :IN SB-PCL::INSTALL-INITIAL-CONSTRUCTOR) #<CLOSURE (FLET SWANK::WRITE-OUTPUT :IN SWANK::CALL/TRUNCATED-OUTPUT-TO-STRING) {1002CC973B}>)
126: (SWANK::CALL/TRUNCATED-OUTPUT-TO-STRING 65536 #<CLOSURE (LAMBDA (STREAM) :IN SWANK::%%CONDITION-MESSAGE) {1002CC96FB}> "..")
127: (SWANK::%CONDITION-MESSAGE #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929054>)
128: (SWANK::CLOSE-CONNECTION% #<SWANK::MULTITHREADED-CONNECTION {1002417153}> #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929054> NIL)
129: (SWANK::SENTINEL-SERVE (:CLOSE-CONNECTION #<SWANK::MULTITHREADED-CONNECTION {1002417153}> #<TYPE-ERROR expected-type: "(UNSIGNED-BYTE 62)"datum: -475929054> NIL))
130: (SWANK::SENTINEL)
131: ((FLET #:WITHOUT-INTERRUPTS-BODY-1139 :IN SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE))
132: ((FLET SB-THREAD::WITH-MUTEX-THUNK :IN SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE))
133: ((FLET #:WITHOUT-INTERRUPTS-BODY-359 :IN SB-THREAD::CALL-WITH-MUTEX))
134: (SB-THREAD::CALL-WITH-MUTEX #<CLOSURE (FLET SB-THREAD::WITH-MUTEX-THUNK :IN SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE) {7FFFF5EAED6B}> #<SB-THREAD:MUTEX "thread result lock" owner: #<SB-THREAD:THREAD "Swank Sentinel" RUNNING {10021A3183}>> NIL T NIL)
135: (SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE #<SB-THREAD:THREAD "Swank Sentinel" RUNNING {10021A3183}> NIL #<FUNCTION SWANK::SENTINEL> (#<SB-THREAD:THREAD "Swank Sentinel" RUNNING {10021A3183}> #<SB-THREAD:THREAD "main thread" RUNNING {1001E06C23}>) NIL NIL NIL NIL)
136: ("foreign function: call_into_lisp")
137: ("foreign function: new_thread_trampoline")
Help! ERROR-ERROR is 3 levels deep. Will try to THROW this thread to the toplevel.
; 
; compilation unit aborted
;   caught 1 fatal ERROR condition
```

I'm on spacemacs develop on SBCL 1.3.14-debian, slime is in version slime-20171106.1331. Was doing some basic development and compilation work in meantime.

I see a `(ERROR TYPE-ERROR :DATUM -475929070 :EXPECTED-TYPE (UNSIGNED-BYTE 62))` somewhere in there. Unsigned values definitely can't be negative, so that's a type error.