Fixes crashing issue when jsYaml.safeload throws an exception

[stjeffrey]

We had an issue using openapi-comment-parser when some Kubernetes yaml files were in our source folder.
Some of our yamls had '---' which allows us to combine multiple K8s objects in a single file.
After some digging we found the issue to be JSYaml that threw an exception and the parsefile function assumes that if you catch an exception there will be a mark object which isn't the case here.

The code simply checks for e.mark and if it doesn't exist it returns line and column 0 instead.