clippy executables should not return non-zero unless catastrophe #78
Description
Right now any errors that occur (see rename_series, for example) that are limited to the function being called and that do not create instabilities or inconsistency nevertheless result in a nonzero return code for the clippy executable.
What we should probably do instead is to create a JSON return object called "errors" and "warnings" and then let the (python) front end display the error / raise the exception, instead of what happens now, which is that the return 1 then causes the python to throw a NonZeroReturnError.
Issue for discussion.