[CRASH] When ripple deleting in certain circumstances

[jazztickets]

Commit Hash 70690c5

Platform Arch Linux

Summary I've found that when ripple deleting a few clips (possibly involving cross fades or text nodes), olive crashes.

Steps to Reproduce

1. Create a few clips on the timeline, and add text nodes and/or crossfades between them
2. Highlight some of the clips at the beginning, but not all clips
3. Shift+delete to ripple delete.

Here's one scenario that crashes:

Crash Report

Additional Information

I loaded up Olive in a debugger and it turns out the track variable is null on line 390: https://github.com/olive-editor/olive/blob/70690c5b54bbd7763823d1632b348ed1462b2cb0/app/timeline/timelineundoripple.cpp#L390

Adding something like this fixes the crashes:

    Track *track = region.first;
    if(!track) {
      qWarning() << "Track is null!";
      continue;
    }

If it's not supposed to be null, then we got other problems but it's a good idea to check for null here in any case.

[Awesomeplayer98]

I get this same issue. It's definitely related to cross fades.

[ThomasWilshaw]

If you can confirm it's realated to transitions see #1842