improve webpack error messaging/reduce noise

[elyseholladay]

Webpack spits out a ton of useless noise in the terminal logs when running the server.

The error messaging for incorrect/missing dependencies is too vague to be useful; it needs to at least display what types of files or what files are missing, rather than just TypeError: Cannot read property 'entryPoints' of undefined

Also, general noise should be reduced by only displaying relevant info.