stack overflow error when trying to assemble files with recursive include directives

steps to reproduce:

create file a.asm with contents #include "b.asm"
create file b.asm with contents #include "a.asm"
execute customasm a.asm

output of customasm a.asm:

customasm v0.10.6
assembling `a.asm`...

thread 'main' has overflowed its stack
fatal runtime error: stack overflow
Aborted (core dumped)

I think the assembler should terminate gracefully instead of crashing. (maybe when an include depth limit is reached?) The error also occurs when a file includes itself, maybe this should't be allowed in the first place?

hlorenzi / customasm

stack overflow error when trying to assemble files with recursive include directives #29