I have big problems in a program and I can't understand what happens.
After hours, the program crashes and lands into the debugger. Once in the debugger, I am trying to understand the problem but It looks like there should have been big problems under the cover: I can't even inspect the object, the debugger telling me the intrisic structure is invalid:


0] frame 10
10] L
SB-DEBUG::ARG-0  =  #<MESSAGE {2528A9C9}>

10] (sb-debug:arg 0)

#<MESSAGE {2528A9C9}>
10] (slot-boundp (sb-debug:arg 0) 'src)

debugger invoked on a TYPE-ERROR in thread #<THREAD "initial thread" {A6CC799}>:
  The value #<invalid object #x8A88FAD7> is not of type (SIMPLE-ARRAY T (*)).

Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.


Note i am note using any exotic features such as multithreading but only common lisp features
Any idea of what else to do ?