Loop ends at the start, negative seconds timer

### System Information

Steam OS

### LMMS Version(s)

latest nightly appimage

### Most Recent Working Version

_No response_

### Bug Summary

Open the Piano Roll from the Song Editor, make a single bar loop at the begging. Set the loop's end at the first bar and click the play button to see it it loop infinitely with a negative timer.

### Expected Behaviour

Setting the end of the loop at the same bar it starts shouldn't be possible because it creates this bug.

### Steps To Reproduce

Open the Piano Roll from the Song Editor, make a single bar loop at the begging. Set the loop's end at the first bar and click the play button to see it it loop infinitely with a negative timer.

### Logs

_No response_

### Screenshots / Minimum Reproducible Project


### Please search the issue tracker for existing bug reports before submitting your own.

- [x] I have searched all existing issues and confirmed that this is not a duplicate.

Start by reproducing the loop behavior from the Song Editor's Piano Roll with the loop start and end on the first bar, then inspect the Piano Roll loop controls and playback timer. Done means equal loop boundaries cannot create an infinite loop and the timer does not become negative.

Written by the indexing model from the issue text.