[CLI] dependencies crashing

[kevinchern]

Current code not robust. Reproduce by creating a dependencies.txt as follows:

ca.ubc.stat:conifer:2.0.4

note empty line NOT

ca.ubc.stat:conifer:2.0.4

call blang cli and it should crash. standalone compiler tries to do compile ''

[alexandrebouchard]

Good point, and we might as well add a bit more validation that each line should have the format "^.+[:].+[:].+$" and print a meaningful message if it does not.

[kevinchern]

we will send a pull request soon :)!