Better error handling?

[dschaeffer17]

There are several minor (edge case) bugs in DataView that seem to crash the program (at least when run from terminal). While eventually these can be corrected, can an error handler be implemented that would catch these errors first?

[pheuer]

I've added an error catching statement for ValueErrors around the plotting routine to try and make these non-fatal. Ideas for other ways of making it more stable welcome?