class WeirdDict(dict): pass
ns = {}
exec("def __create_fn__():\n return a", WeirdDict({None: None}), ns)
ns['__create_fn__']()

Program received signal SIGSEGV, Segmentation fault.
_PyEval_LoadGlobalStackRef (globals=<optimized out>, builtins=<optimized out>, name=0x555555aeace0 <_PyRuntime+80128>, writeto=0x7ffff7fb00f8) at Python/ceval.c:3317
3317            *writeto = PyStackRef_FromPyObjectSteal(res);
(gdb) bt
#0  _PyEval_LoadGlobalStackRef (globals=<optimized out>, builtins=<optimized out>,
    name=0x555555aeace0 <_PyRuntime+80128>, writeto=0x7ffff7fb00f8) at Python/ceval.c:3317
#1  0x00005555555e22f2 in _PyEval_EvalFrameDefault (tstate=0x555555b24178 <_PyRuntime+314776>,
    frame=<optimized out>, throwflag=<optimized out>) at Python/generated_cases.c.h:9073
#2  0x00005555557ab807 in _PyEval_EvalFrame (throwflag=0, frame=0x7ffff7fb0020,
    tstate=0x555555b24178 <_PyRuntime+314776>) at ./Include/internal/pycore_ceval.h:119
#3  _PyEval_Vector (args=0x0, argcount=0, kwnames=0x0, locals=0x7ffff7a4d240, func=0x7ffff7a50f60,
    tstate=0x555555b24178 <_PyRuntime+314776>) at Python/ceval.c:1913
#4  PyEval_EvalCode (co=co@entry=0x7ffff7bf5920, globals=globals@entry=0x7ffff7a4d240,
    locals=locals@entry=0x7ffff7a4d240) at Python/ceval.c:829
#5  0x000055555581f3bc in run_eval_code_obj (locals=0x7ffff7a4d240, globals=0x7ffff7a4d240,
    co=0x7ffff7bf5920, tstate=0x555555b24178 <_PyRuntime+314776>) at Python/pythonrun.c:1365
#6  run_mod (mod=<optimized out>, filename=filename@entry=0x7ffff7a066b0,
    globals=globals@entry=0x7ffff7a4d240, locals=locals@entry=0x7ffff7a4d240,
    flags=flags@entry=0x7fffffffdc18, arena=arena@entry=0x7ffff7b5e210, interactive_src=0x0,
    generate_new_source=0) at Python/pythonrun.c:1436
#7  0x0000555555821456 in pyrun_file (flags=0x7fffffffdc18, closeit=1, locals=0x7ffff7a4d240,
    globals=0x7ffff7a4d240, start=257, filename=0x7ffff7a066b0, fp=0x555555b97510)
    at Python/pythonrun.c:1293

python: ./Include/internal/pycore_stackref.h:447: PyStackRef_FromPyObjectSteal: Assertion `obj != NULL' failed.

Program received signal SIGABRT, Aborted.
__pthread_kill_implementation (no_tid=0, signo=6, threadid=140737350580032) at ./nptl/pthread_kill.c:44
44      ./nptl/pthread_kill.c: No such file or directory.
(gdb) bt
#0  __pthread_kill_implementation (no_tid=0, signo=6, threadid=140737350580032) at ./nptl/pthread_kill.c:44
#1  __pthread_kill_internal (signo=6, threadid=140737350580032) at ./nptl/pthread_kill.c:78
#2  __GI___pthread_kill (threadid=140737350580032, signo=signo@entry=6) at ./nptl/pthread_kill.c:89
#3  0x00007ffff7ce0476 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4  0x00007ffff7cc67f3 in __GI_abort () at ./stdlib/abort.c:79
#5  0x00007ffff7cc671b in __assert_fail_base (
    fmt=0x7ffff7e7b130 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n",
    assertion=0x555555a5971d "obj != NULL", file=0x5555559dc630 "./Include/internal/pycore_stackref.h",
    line=447, function=<optimized out>) at ./assert/assert.c:94
#6  0x00007ffff7cd7e96 in __GI___assert_fail (assertion=assertion@entry=0x555555a5971d "obj != NULL",
    file=file@entry=0x5555559dc630 "./Include/internal/pycore_stackref.h", line=line@entry=447,
    function=function@entry=0x555555a42180 <__PRETTY_FUNCTION__.23> "PyStackRef_FromPyObjectSteal")
    at ./assert/assert.c:103
#7  0x0000555555829da7 in PyStackRef_FromPyObjectSteal (obj=<optimized out>)
    at ./Include/internal/pycore_stackref.h:447
#8  _PyEval_LoadGlobalStackRef (globals=<optimized out>, builtins=<optimized out>, name='a',
    writeto=writeto@entry=0x7ffff7fb00f8) at Python/ceval.c:3312
#9  0x000055555584e4ba in _PyEval_EvalFrameDefault (
    tstate=tstate@entry=0x555555c69558 <_PyRuntime+330424>, frame=0x7ffff7fb00a8,
    frame@entry=0x7ffff7fb0020, throwflag=throwflag@entry=0) at Python/generated_cases.c.h:9086
#10 0x000055555585cd69 in _PyEval_EvalFrame (throwflag=0, frame=0x7ffff7fb0020,
    tstate=0x555555c69558 <_PyRuntime+330424>) at ./Include/internal/pycore_ceval.h:119