Apparently minTermLength fix from @davidhurley's didn't include a default value for the setting. So it was using 0 as minimum length (until you save the com_params config). I added an extra this.value check to be sure that an empty tag is never going to be added even if someone manages to use 0 as minTermLength (which should not be possible because the minimum in config is 1).
@test: After applying the patch, I can save the article after adding a tag using Enter.