The value NIL is not of type REAL when binding SB-KERNEL::N1

[Paul F. Dietz]

(lambda (b)
  (case 0 ((6 nil) 0) ((2 1 -3 4) b) (t 0)))

==>

The value
  NIL
is not of type
  REAL
when binding SB-KERNEL::N1
   [Condition of type TYPE-ERROR]

Restarts:
 0: [RETRY] Retry SLIME REPL evaluation request.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT] abort thread (#<THREAD tid=5898 "repl-thread" RUNNING {1000EF8003}>)

Backtrace:
  0: (< NIL 6)
  1: ((LABELS SB-IMPL::RECUR :IN SB-IMPL::STABLE-SORT-LIST) ((6 . #1=#<SB-C::CBLOCK 3 :START c1 {1008362953}>) (NIL . #1#) (2 . #2=#<SB-C::CBLOCK 4 :START c2 {1008361DE3}>) (1 . #2#) (-3 . #2#) (4 . #2#)) ..
  2: ((LABELS SB-IMPL::RECUR :IN SB-IMPL::STABLE-SORT-LIST) #<unavailable argument> 6)
  3: (SB-IMPL::STABLE-SORT-LIST ((6 . #1=#<SB-C::CBLOCK 3 :START c1 {1008362953}>) (NIL . #1#) (2 . #2=#<SB-C::CBLOCK 4 :START c2 {1008361DE3}>) (1 . #2#) (-3 . #2#) (4 . #2#)) #<FUNCTION <> #<FUNCTION CAR..
  4: (SB-C::PREPARE-JUMP-TABLE-TARGETS #<SB-C::LVAR 3 {10083526A3}> ((6 . #1=#<SB-C::CBLOCK 3 :START c1 {1008362953}>) (NIL . #1#) (2 . #2=#<SB-C::CBLOCK 4 :START c2 {1008361DE3}>) (1 . #2#) (-3 . #2#) (4 ..
  5: (SB-C::IR2-CONVERT-JUMP-TABLE #<SB-C:JUMP-TABLE :INDEX #<SB-C::LVAR 3 {10083526A3}> :TARGETS ((6 . #1=#<SB-C::CBLOCK 3 :START c1 {1008362953}>) (NIL . #1#) (2 . #2=#<SB-C::CBLOCK 4 :START c2 {1008361D..
  6: (SB-C::IR2-CONVERT-BLOCK #<SB-C::CBLOCK 1 :START c4 {1008351AD3}>)
  7: (SB-C:IR2-CONVERT #<SB-C:COMPONENT :NAME "<unknown>" {1008354F23}>)
  8: (SB-C::%COMPILE-COMPONENT #<SB-C:COMPONENT :NAME "<unknown>" {1008354F23}>)
  9: (SB-C::COMPILE-COMPONENT #<SB-C:COMPONENT :NAME "<unknown>" {1008354F23}>)
 10: (SB-C::%COMPILE (LAMBDA (B) (CASE 0 (# 0) (# B) (T 0))) NIL NIL)
[...]

x86-64, "2.4.2.200-8a4a8dd68"