The value NIL is not of type SEQUENCE

[Paul F. Dietz]

(defun bug371 ()
  (let* ((s (coerce "" 'simple-base-string))
         (lam
           `(lambda (p2 p3)
              (declare (optimize (speed 3))
                       (type (eql ,s) p2)
                       (type (or symbol (simple-base-string 8)) p3))
              (concatenate 'base-string p2 p3))))
    (funcall (compile nil lam) s nil)))

(bug371) ==>

The value
  NIL
is not of type
  SEQUENCE
   [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=23918 "repl-thread" RUNNING {100869E3F3}>)

Backtrace:
  0: ((LAMBDA (P2 P3)) #<unused argument> #<unavailable argument>)
  1: (SB-INT:SIMPLE-EVAL-IN-LEXENV (BUG371) #<NULL-LEXENV>)
  2: (EVAL (BUG371))
[...]

x86-64, "2.4.3.13-971963a9d"