The problem is, the error is discovered by the low-level renderer, not by the setShaderAuto() call. So there’s no easy way to send an error message back to the application. There’s no single Panda call that has failed! It just wasn’t able to render the scene.
It would be possible to work around this, but it would be complicated. I’m not opposed to solving it, but it’s not going to happen in the short term (unless you’d like to offer patches?) In any case, it still wouldn’t solve every problem; and that’s why I suggest just punting anyway.
David