fix(robo): show error when importing config files

[Pkmmte]

Sometimes importing a config file fails if there's a runtime error in its global scope, and Robo.js doesn't tell us why. It should.

The runtime error can be pretty much anything. Wrong import, field access on null object, null assertions, intentional errors, etc.

I don't think these errors should prevent the Robo from starting. If anything, it should start as if there were no custom options provided at all. We just need to let the user know why.