errors during build result in a successful exit code

[dlockhart]

When an error occurs during the wcs build process, the exit code is a successful 0. This causes CI systems to think things passed when in fact they did not.

To reproduce: cause an error somewhere in vulcanize, for example by importing a file that doesn't exist. Then output the exit code echo $? and see that you get 0 instead of a non-zero failure value.