[Bug] Pattern Crash When Switching Songs

[N-SPC700]

Bug description

Program crashes when what seemingly is pattern row ID not being valid on the next song.

How to reproduce

1. Open the attached module: mm1gb_weirdbug.zip
2. Go to the 3rd song in the module (Cut Man)
3. Click on the pattern editor on the left, go to the last pattern row
4. Change the song to the next one (Elec Man)
5. Tracker should crash with an "Unexpected Error";
   [Uncaught exception] Type: class std::invalid_argument What: order does not exist

I cannot say for sure but it's likely trying to stay at the same pattern row (07) in the next song, despite that not being possible in the Elec Man song due to it containing only one pattern (00).

Information

• OS: Windows 10 20H2
• Architecture: x64
• Trackerboy version: 0.6.0

[N-SPC700]

also tested this in the previous build 0.5.0 nightly. it doesn't seem to exhibit the same issue.

[stoneface86]

Was able to reproduce, exception occurs in OrderGrid::paintEvent line 328

OrderGrid's mPatternStart and mPatternEnd members are invalid, which caused the exception during the paint event.
My guess is that OrderGrid::updatePatternRange() is not getting called when it should.

[stoneface86]

Scratch that, it was caused by SongModel emitting its *Changed signals on song change, causing the PatternModel to throw an exception when handling the patternSizeChanged signal.

Solution:

• SongModel should instead emit a new signal, reloaded and have the SongEditor handle that signal