document that parseLine can return null

[travellingprog]

For some reason, at the top of the stack of one particular error, I have only the error message, rather than a line with a filename. Therefore, my code ran into an issue because it called stack.parseLine(firstLineOfStack) and assumed this method would return an object. I did not realize that this method could return null. I assumed that if it could not parse a line, it would return an object where the properties are set to empty values, or perhaps throw an error.

I believe this possibility should be documented.

But thanks for the great library!

[conartist6]

This is fixed in stack-tools, which throws an error if a stack frame cannot be parsed. It can also do this more safely because unparseable stack frames are likely to be messages from nested errors, for example those produced by nested-error-stacks. stack-tools offers first class support for this, for example by allowing you to write this:

cleanErrors(parseErrors(error), frame => shouldRemoveFrame(frame));