require()'ing a missing dependency returns null instead of throwing

[requirejs]

require()'ing a missing dependency returns null instead of throwing

[jrburke]

I just pushed a change to the orderless tree for this. If a module is not available, it will throw a string saying "abc missing xyz", meaning that abc tried to load xyz and it was not available. While the message is terse I think it gives enough info.

[jrburke]

I went ahead and pushed the changes into master and did a 0.0.3 release. Closing this out now.