[Bug demangler/78944] null pointer in demangler

[vanyacpp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78944

--- Comment #2 from Ivan Sorokin <vanyacpp at gmail dot com> ---
Another very rare crash discovered by my fuzzer: _Z1fAqu4SmFG1n3_a.