Improve error messages

[dylanirlbeck]

• [x] Include suggestions i.e. Did you mean 'flex-row'?. We'll use the Hamming distance for this since there's a relatively small number of valid class names (we'll just extend the end of the smaller string with whitespace to make them equal length).
• [x] Handle parsing errors more elegantly
• [ ] Highlight the specific className that failed (rather than the entire string) -> This might not be possible, but let's see