Increase error output stack depth to 10 from 5

Found 5 a little restrictive for array matching. 

Maintaining style resulted in a lot of lines creating test objects - happy to rebase into `{"a": {"b": {"c": {"d": {"e": {"f": {"g": {"h": {"i": {"j": nested}}}}}}}}}}` format if you'd prefer. Also tried to maintain column width - will change if desired.

Thanks.