Draft: E3-713: update exception handling

This MR stops the configuration file exceptions being silently trapped, which allows better testing of the function to be performed.

A couple of test conditions were added for configuration file/module combinations that are known to not exist. I'm not sure that this is the best way or place to handle this - it feels a bit non-Python to do it this way. I'm interested in any feedback on the two if...: continue statements, and if there is a better way of handling this.