Comment 1 for bug 1272742

similar test cases have also errored with

Index 5550 out of bounds for (SIMPLE-ARRAY (UNSIGNED-BYTE 64)
                              (4096)), should be nonnegative and <4096.
   [Condition of type SB-INT:INVALID-ARRAY-INDEX-ERROR]

Restarts:
 0: [ABORT] Abort thread (#<THREAD RUNNING {10041B62E3}>)

Backtrace:
  0: ((FLET #:BODY-FUN-834 :IN SB-KERNEL:%PUTHASH))
  1: (SB-KERNEL:%PUTHASH #<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185EC163}> #<HASH-TABLE :TEST EQL :COUNT 10559 {1000311F83}> ((:FLUSH #1=#<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185EC163}>) (:FLUSH #1#) ..
      Locals:
        SB-DEBUG::ARG-0 = #<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185EC163}>
        SB-DEBUG::ARG-1 = #<HASH-TABLE :TEST EQL :COUNT 10559 {1000311F83}>
        SB-DEBUG::ARG-2 = ((:FLUSH #<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185EC163}>) (:FLUSH #<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185EC163}>) (:FLUSH #<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185EC163}>) ..)
  2: (SB-KERNEL::%ENSURE-CLASSOID-VALID #<SB-KERNEL:STANDARD-CLASSOID F> #<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185864C3}> "typep")
      Locals:
        SB-DEBUG::ARG-0 = #<SB-KERNEL:STANDARD-CLASSOID F>
        SB-DEBUG::ARG-1 = #<SB-PCL::WRAPPER #<STANDARD-CLASS F> {10185864C3}>
        SB-DEBUG::ARG-2 = "typep"
  3: (SB-KERNEL:CLASSOID-TYPEP #<unavailable argument> #<unavailable argument> #<unavailable argument>)
      [No Locals]

where most of the backtrace seems to have been optimized away by TCO, but probably looks something like
typep -> %typep -> %%typep -> classoid-typep -> %ensure-classoid-valid -> %force-cache-flushes -> %invalidate-wrapper -> (setf (gethash nwrapper *previous-nwrappers*))
with *previous-nwrappers* being the hash table in the error