Handle error case - no error string

[mwobensmith]

For whatever reason, we sometimes get into a situation where there is no error string to parse, and we fail. This means that the log can't be generated. We need to address this somehow, at the very least with a try/except block so that we can work past this.

Ideally we'd find out why we haven't gotten the short error message in the first place, but this is a short-term solution.

[cr]

If I understand @franziskuskiefer correctly, we must catch this in JS land. The workaround there is to fall back to an empty string when reading the message property fails (see #159). Your code should instead check for an empty string and handle it accordingly.