Bad color code breaks compilation

[mortoray]

A user entered Color="#36" which causes UX compilation to break, and Preview to fail to show anything.

It's clearly a user-error, but the abrupt break in Preview caused them distress -- they had no idea what was wrong as they were making minor changes and suddenly everything went away.

This issue might be more of a problem of interplay between UX compiler and Preview in cases of broken code. It's not clear exactly what should happen.

[AndrewEQ]

If not a valid color code, color should not be attempted to be changed and error message with reason should be displayed.

[ichan-mb]

works on Fuse X