Stack overflow crash cases

[blt]

Hello,

I've started a fuzzing project for serde-yaml and have discovered some failure cases. As an example:

$ cat crash_cases/id\:000000\,sig\:06\,src\:001416\,op\:flip2\,pos\:2 | ./target/debug/serde_yaml_fuzz

thread 'main' has overflowed its stack
fatal runtime error: stack overflow
Aborted

As of this writing both cases discovered are contained in commit 23fdce4bfdad162acae28ca9897690bfca9d43ec. Instructions to reproduce my AFL setup are in-repo. The examples in crash_cases can be run without AFL, as above.

Please do let me know if I can provide any further information.

[dtolnay]

Thanks! This was fixed in #105.