Null/Empty/Invalid Jumps should either not interfere with playback or should report error
If I create a jump and use either an empty string or an undefined marker for both "Jump to", "Play Until", and "Continue at", then playback will halt second time through the next repeat:
I suggest that the expected defined behavior for an empty string for all markers should be that the jump is ignored and result in playback identical to no jump existing (I'm calling it a null or empty jump). There may be valid reasons for having a null jump: for instance I often want to write specific text instructions to the performs about how to repeat and solo and want to benefit from the right-justification property that jump instructions have*, but I don't want the musescore generated playback to actually have those jumps. Or maybe I haven't finished my score and haven't really figured out every marker yet, but still want sane playback.
If the jump instead has undefined (but non-empty) strings for any marker, then I suggest that the jump text and the undefined marker strings be displayed red when viewed in musescore (like notes with pitches out of range are) so user can easily spot them. (I've wasted hours trying to track misnamed & empty markers...felt like debugging computer code for loops and branches!).
*Note, I'm currently working around by creating System text at the very final note of the measure and giving it Right Repeat Text Style, however this causes the text to end at the leftmost position of the final note, while I really want the text to go all the way to the barline. If I create the text at the beginning of next measure, then unfortunately any line breaks will cause text to disappear to next line's margin.