b56daddda6
An earlier commit accidentally removed too much code. This is now
restored, so that when keyframe insertion fails, at least on stdout it's
logged which F-Curve caused this failure.
8dbd167e80 did improve the error
reporting, but even that does not explicitly mention which F-Curves
caused those errors (for good reason, as cluttering the UI would be very
simple then).
Pull Request: https://projects.blender.org/blender/blender/pulls/121527