Custom Cargo Command to Show Only Errors (Avoid Setting RustFLAGS Every Time)

I don't think that this is the right approach to this problem. I fully agree that there is a problem though. It can be really hard to see errors hidden within lots of different warnings that are usually not relevant when developing. We don't need config or options to handle this better, we need better defaults. I think it would be nice if we had a way to make the errors more visible than the warnings. Maybe something like re-printing errors at the end of the build log if there were several warnings?