Graceful failure and error reporting when input data prevents proper drawing

[moarrubber]

Currently issues in the input data result in NaN and undefined variables causing errors deep in the libraries called. It would be better to report these errors early and with details so that the data set can be corrected.

If there are errors in the geometry data should the bike be drawn? I would think not.
One thought for implementation would be to have a pop up, or a text box within the drawing box.
Error should include the reason for failure, the bike it failed on, and what fields were missing/incorrect.
It may have to deal with failures from multiple bikes in the comparison.

[moarrubber]

One way it could look:

[jdtoy]

If there are errors in the geometry data should the bike be drawn?

Difficult to answer. My gut says that trying to draw as much of the bike as possible is a better outcome for the user than not drawing the bike at all

For example:

• the lack of seatpost, fork, or wheel data should not prevent the frame from being drawn.
• In a 'wheels on ground' view it would not be possible to draw a bike without bottom bracket height or wheel sizing, but that frame should appear in a bb-centred view.

Error should include the reason for failure, the bike it failed on, and what fields were missing/incorrect.

Yes. But, I'd question the value of showing this to the user, particularly if the missing information doesn't exist, or they can't easily fix it?

Perhaps a blanket visual error "Some bikes, or parts of bikes, could not be drawn due to missing data." would be sufficient for non technical/non geeky users, with the full reason for the error being logged to the JS console?