Fix bug introduced by warning logs (errors didn't print)

Not sure how I missed that this would be an issue but after my warning logging by redirecting the compiler's stderr output to a file, errors no longer printed as they were just getting sent to that file (of course) and then make will immediately stop when any command returns a non-zero exit code so the `cat <warning file>` command wasn't being reached.  I don't know of a way to avoid the errors going to the warning logs (seems ok to me), so now if compilation fails I print that warning log file and exit with a non-zero code.