(defun foo ()
   'foo)

;;;; ------    Error code ---------

The value NIL is not of type SB-C:POLICY.
   [Condition of type TYPE-ERROR]

Restarts:
 0: [ABORT] Abort compilation.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT] abort thread (#<THREAD "worker" RUNNING {10066A5BA3}>)

Backtrace:
  0: (SB-C::POLICY-TO-DECL-SPEC NIL T NIL)
  1: (RESTRICT-COMPILER-POLICY NIL 0)
  2: (SWANK/SBCL::COMPILER-POLICY NIL)
      Locals:
        QUALITIES = NIL
  3: ((LABELS SWANK/SBCL::CF :IN SWANK/BACKEND:SWANK-COMPILE-STRING))
  4: ((FLET SWANK/BACKEND:CALL-WITH-COMPILATION-HOOKS :IN "/home/jreynoso/quicklisp/dists/quicklisp/software/slime-2.13/swank/sbcl.lisp") #<CLOSURE (LAMBDA NIL :IN SWANK/BACKEND:SWANK-COMPILE-STRING) {1006..
  5: ((FLET SWANK/BACKEND:SWANK-COMPILE-STRING :IN "/home/jreynoso/quicklisp/dists/quicklisp/software/slime-2.13/swank/sbcl.lisp") " (defun foo () ..)
  6: ((LAMBDA NIL :IN SWANK:COMPILE-STRING-FOR-EMACS))
  7: ((LAMBDA NIL :IN SWANK::COLLECT-NOTES))
  8: (SWANK::MEASURE-TIME-INTERVAL #<CLOSURE (LAMBDA NIL :IN SWANK::COLLECT-NOTES) {10066B449B}>)
  9: (SWANK::COLLECT-NOTES #<CLOSURE (LAMBDA NIL :IN SWANK:COMPILE-STRING-FOR-EMACS) {10066B445B}>)
 10: (SWANK::CALL-WITH-BUFFER-SYNTAX NIL #<CLOSURE (LAMBDA NIL :IN SWANK:COMPILE-STRING-FOR-EMACS) {10066B441B}>)
 11: (SB-INT:SIMPLE-EVAL-IN-LEXENV (SWANK:COMPILE-STRING-FOR-EMACS " (defun foo () ..)
 12: (EVAL (SWANK:COMPILE-STRING-FOR-EMACS " (defun foo () ..)
 13: (SWANK:EVAL-FOR-EMACS (SWANK:COMPILE-STRING-FOR-EMACS " (defun foo () ..)
 14: ((LAMBDA NIL :IN SWANK::SPAWN-WORKER-THREAD))
 15: (SWANK/SBCL::CALL-WITH-BREAK-HOOK #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<FUNCTION (LAMBDA NIL :IN SWANK::SPAWN-WORKER-THREAD) {1008A6C49B}>)
 16: ((FLET SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK :IN "/home/jreynoso/quicklisp/dists/quicklisp/software/slime-2.13/swank/sbcl.lisp") #<FUNCTION SWANK:SWANK-DEBUGGER-HOOK> #<FUNCTION (LAMBDA NIL :IN SWANK:..
 17: (SWANK::CALL-WITH-BINDINGS ((*STANDARD-OUTPUT* . #1=#<SWANK/GRAY::SLIME-OUTPUT-STREAM {1004F2C963}>) (*STANDARD-INPUT* . #2=#<SWANK/GRAY::SLIME-INPUT-STREAM {1004E5D333}>) (*TRACE-OUTPUT* . #1#) (*ERR..
 18: ((LAMBDA NIL :IN SWANK::SPAWN-WORKER-THREAD))
 19: ((FLET #:WITHOUT-INTERRUPTS-BODY-1156 :IN SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE))
 20: ((FLET SB-THREAD::WITH-MUTEX-THUNK :IN SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE))
 21: ((FLET #:WITHOUT-INTERRUPTS-BODY-608 :IN SB-THREAD::CALL-WITH-MUTEX))
 22: (SB-THREAD::CALL-WITH-MUTEX #<CLOSURE (FLET SB-THREAD::WITH-MUTEX-THUNK :IN SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE) {7FFFF1336D5B}> #<SB-THREAD:MUTEX "thread result lock" owner: #<SB-THREAD:THR..
 23: (SB-THREAD::INITIAL-THREAD-FUNCTION-TRAMPOLINE #<SB-THREAD:THREAD "worker" RUNNING {10066A5BA3}> NIL #<CLOSURE (LAMBDA NIL :IN SWANK::SPAWN-WORKER-THREAD) {10066A5B2B}> (#<SB-THREAD:THREAD "worker" RU..
 24: ("foreign function: call_into_lisp")
 25: ("foreign function: new_thread_trampoline")