The value NIL is not of type SB-C::IR2-LVAR

[Paul F. Dietz]

(lambda (a b)
  (declare (type fixnum b))
  (/= 0 (setq a 1) b))

==>

The value
  NIL
is not of type
  SB-C::IR2-LVAR
   [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=4253 "repl-thread" RUNNING {1000F80003}>)

Backtrace:
  0: (SB-C::LVAR-RESULT-TNS #<SB-C::LVAR 1 {100C179FD3}> (#<SB-KERNEL:NAMED-TYPE T>) NIL NIL)
  1: (SB-C::IR2-CONVERT-SET #<SB-C::CSET :VAR #<SB-C::LAMBDA-VAR :%SOURCE-NAME A {100C1700E3}> :VALUE #<SB-C::REF :LEAF #<SB-KERNEL:CONSTANT :VALUE 1 {100C173883}> {100C1738E3}> {100C173943}> #<SB-C::IR2-..
  2: (SB-C::IR2-CONVERT-BLOCK #<SB-C::CBLOCK 3 :START c2 {100C170783}>)
  3: (SB-C:IR2-CONVERT #<SB-C:COMPONENT :NAME "<unknown>" {100C174DF3}>)
  4: (SB-C::%COMPILE-COMPONENT #<SB-C:COMPONENT :NAME "<unknown>" {100C174DF3}>)
  5: (SB-C::COMPILE-COMPONENT #<SB-C:COMPONENT :NAME "<unknown>" {100C174DF3}>)
  6: (SB-C::%COMPILE (LAMBDA (A B) (DECLARE (TYPE FIXNUM B)) (/= 0 (SETQ A 1) B)) NIL NIL)
[...]

x86-64, "2.4.1.222-af373d354"