Memory Fault error for wrong :keyword-normalizer value

[MattSkinner]

Noticed that if I specify t for :keyword-normalizer that I get a message about unhandled memory fault.

(jonathan:parse response :keyword-normalizer t)

causes:

#<THREAD "main thread" RUNNING {1001F0EAE3}>:
  Unhandled memory fault at #x0.

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.

(SB-SYS:MEMORY-FAULT-ERROR)
0] backtrace 10

Backtrace for: #<SB-THREAD:THREAD "main thread" RUNNING {1001F0EAE3}>
0: (SB-SYS:MEMORY-FAULT-ERROR)
1: ("foreign function: call_into_lisp")
2: ("foreign function: post_signal_tramp")
3: ((LABELS JONATHAN.DECODE::DISPATCH :IN JONATHAN.DECODE:PARSE) #<unavailable argument> #<unavailable argument>)
4: ((LABELS JONATHAN.DECODE::DISPATCH :IN JONATHAN.DECODE:PARSE) #<unavailable argument> #<unavailable argument>)
5: (JONATHAN.DECODE:PARSE #<unavailable argument> :AS #<unavailable argument> :JUNK-ALLOWED #<unavailable argument> :KEYWORDS-TO-READ #<unavailable argument> :KEYWORD-NORMALIZER #<unavailable argument> :NORMALIZE-ALL #<unavailable argument> :EXCLUDE-NORMALIZE-KEYS #<unavailable argument> :UNESCAPE-UNICODE-ESCAPE-SEQUENCE #<unavailable argument>)
6: (SB-INT:SIMPLE-EVAL-IN-LEXENV (JONATHAN.DECODE:PARSE "{\"name\"}" :KEYWORD-NORMALIZER T) #<NULL-LEXENV>)
7: (EVAL (JONATHAN.DECODE:PARSE "{\"name\"}" :KEYWORD-NORMALIZER T))
8: (INTERACTIVE-EVAL (JONATHAN.DECODE:PARSE "{\"name\"}" :KEYWORD-NORMALIZER T) :EVAL NIL)
9: (SB-IMPL::REPL-FUN NIL)