Heavier error colors?

[Felienne]

A first version of #4165 introduced error colors that very clearly show something is amiss:

Level 5 and above

• Go to http://localhost:8080/hedy/5#default
• Paste this code and observe formatting:

print 'I'm babysitting my sister's kids'
print 'What's more fun than that?'
print 'This is an unterminated quotes string
print "Again, but with double quotes 

I actually like this idea but I decided to park it here because it deviates a bit from what we do currently. I would love to explore this idea more, but I think we need to make some sort of plan.

My main concern is consistency, does it make sense to kids that they get this "service" for a missing quote, but not in other scenarios like a missing indent? I can already hear my students yelling "BUT TEACHER IT DID NOT MAKE ANYTHING PINK HOW COULD I KNOW IT WAS WRONG?" :D But on the other hand, it will certainly help so maybe we should not worry about it not helping everywhere?

And if we do go this path, here are a few other situations where we could do it this way, like a forgotten ' and other things that are regex-able.