Comment 5 for bug 1429520

Afaict, we do handle errors sanely. There is a default sane pprint-dispatch table that the debugger uses.
This is only a problem in Slime.

* (defun bork (x) x (error "Oh oh"))
BORK
* (set-pprint-dispatch '(satisfies bork) (lambda (stream obj) (format stream "[~A]" (type-of obj))))
debugger invoked on a SIMPLE-ERROR in thread
#<THREAD "main thread" RUNNING {1002D8E9F3}>:
  Oh oh

Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [ABORT] Exit debugger, returning to top level.

(BORK #<unavailable argument>)
0] *print-pretty*
T
0] (make-hash-table)
#<HASH-TABLE :TEST EQL :COUNT 0 {1002E69283}>
0] (make-array 4)
(make-array 4)
#(0 0 0 0)