#<SB-KERNEL:NAMED-TYPE NIL> fell through ETYPECASE expression.

[Paul F. Dietz]

(compile nil '(lambda () (coerce nil 'vector)))

==>

#<SB-KERNEL:NAMED-TYPE NIL> fell through ETYPECASE expression.
Wanted one of (SB-KERNEL:ARRAY-TYPE SB-KERNEL:UNION-TYPE
               SB-KERNEL:INTERSECTION-TYPE
               SB-KERNEL:MEMBER-TYPE).
   [Condition of type SB-KERNEL:CASE-FAILURE]

Restarts:
 0: [RETRY] Retry SLIME REPL evaluation request.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT] abort thread (#<THREAD tid=2168 "repl-thread" RUNNING {1000B800A3}>)

Backtrace:
  0: ((LABELS SB-KERNEL::DETERMINE :IN SB-KERNEL:CTYPE-ARRAY-SPECIALIZED-ELEMENT-TYPES) #<SB-KERNEL:NAMED-TYPE NIL>)
  1: (SB-KERNEL:CTYPE-ARRAY-SPECIALIZED-ELEMENT-TYPES #<SB-KERNEL:NAMED-TYPE NIL>)
  2: ((SB-C:DEFTRANSFORM REPLACE) #<SB-C::COMBINATION :FUN #<SB-C::REF :LEAF #<SB-C::GLOBAL-VAR :%SOURCE-NAME REPLACE :TYPE #1=#<SB-KERNEL:FUN-TYPE #> :DEFINED-TYPE #1# :WHERE-FROM :DECLARED :KIND :GLOBAL..
  3: (SB-C::IR1-OPTIMIZE-COMBINATION #<SB-C::COMBINATION :FUN #<SB-C::REF :LEAF #<SB-C::GLOBAL-VAR :%SOURCE-NAME REPLACE :TYPE #1=#<SB-KERNEL:FUN-TYPE #> :DEFINED-TYPE #1# :WHERE-FROM :DECLARED :KIND :GLO..
  4: (SB-C::IR1-OPTIMIZE #<SB-C:COMPONENT :NAME "<unknown>" :REANALYZE T {1001201023}> NIL)
  5: (SB-C::IR1-OPTIMIZE-UNTIL-DONE #<SB-C:COMPONENT :NAME "<unknown>" :REANALYZE T {1001201023}>)
  6: (SB-C::IR1-OPTIMIZE-PHASE-1 #<SB-C:COMPONENT :NAME "<unknown>" :REANALYZE T {1001201023}>)
  7: (SB-C::IR1-PHASES #<SB-C:COMPONENT :NAME "<unknown>" :REANALYZE T {1001201023}>)
  8: (SB-C::COMPILE-COMPONENT #<SB-C:COMPONENT :NAME "<unknown>" :REANALYZE T {1001201023}>)
  9: (SB-C::%COMPILE (LAMBDA NIL (COERCE NIL (QUOTE VECTOR))) NIL NIL)
 [...]

x86-64, "2.4.6.111-2c9dfec0c"