[UI] Going back during collection setup can generate a broken traits.json

[Montspy]

A user hit the following error after generating a new collection:

The user did go back to a previous step while generating the traits.json file. After re-trying without going back during collection setup, the problem went away.
The bugged traits.json file was lost but the user will try to reproduce and share the file.

I believe that the traits.json file ended up with "animation": true but with an invalid value for the key "animation_size", causing the above error.

@sk33z3r is there a way to make the collection setup foolproof against going back to previous steps?

[sk33z3r]

I think your assessment is probably correct. It's doable, but a lot of holes in the UI have gone untouched because of the impending PR #47

[sk33z3r]

I'm not too sure what to do about this one. The way that POST works and how I save the file in between each step means it can get a little hairy. I think the whole mechanism will be revisited and fixed with a Mongo implementation, removing the need to store info in static text files, so content can be more dynamic.