Show deps missing msg on deps-related error (fixes #86)

fixes #86
@killerfish What are the other types of errors which show up in here that you're ignoring?  I suspect we didn't even know they were possible!

Regardless, if you call `grep` in a scalar context it will actually give you the number of matches.  When you use it in a conditional, you should get scalar context by default, but I usually like to force it anyway.  Also, if you don't care which characters surround your substring, you can leave it unanchored (as you have) and just check for the substring.

All of that to say this simplifies a bit to:

```perl 
... if (scalar grep { /dependencies/ } values %failed_to_load);
```

I'd probably leave the prints on two lines in a conditional block, too... just because that conditional ends up so far over otherwise.

Regardless, this is all style stuff.. I'm just in that mood, you may feel free to ignore me. :grin: