Improve error logging and display

[sam-f0]

If there is an error parsing a structure (normally due to a bug in the code) it is not shown or logged anywhere. At a minimum we should get it logged to a file so people can report bugs easily. Ideally there should also be a way of showing the error. This could be by including it in the structure window or probably more easily have a key that opens a popup panel with the error details.