[Mu4] fix #327681 illegal repeatsegment crash

[jeetee]

illegal repeatsegment inserted due to a certain open volta, jump and end repeat combination

Resolves: https://musescore.org/en/node/327681

MU4 version of PR #10158
Fixes interpretation order so the end repeat is covered by the open volta if a jump also exists in the same measure.

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[jeetee]

We might want to update Q_ASSERTS to IF_ASSERT_FAILED as per https://github.com/musescore/MuseScore/wiki/Error-handling; but I've not included it here yet, as it would touch more in this file than relevant to the issue.
Perhaps that replacement could be done in a code sweep commit?

[Jojo-Schmitz]

Rebase needed (merge conflict must be in the testing part). Issue came up again in https://musescore.org/en/node/335346

[Jojo-Schmitz]

no Q_ASSERT() without Qt...
So see your own comment at #issuecomment-1000158786

[Jojo-Schmitz]

While I don't claim to fully understand it all, the proposed change does make sense to me ;-)
Also, except for the now removed Q_ASSERT() it is the same code as what I 'stole' for #9000 (rather: picked from #10158), and there it does work.

[jeetee]

@cbjeukendrup would be nice to have this merged in before beta; one less crash to worry about then ;-)

[cbjeukendrup]

It looks good to me, so I've asked @vpereverzev to take a look too, since we're already entering extra careful mode :)

When it comes to asserts, we have two flavours:

• simple (C++ built-in?) assert(…)
• the IF_ASSERT_FAILED macro:

  IF_ASSERT_FAILED(condition) {
      // code that will be run when condition is unexpectedly false
      // (if asserts are enabled (debug build), then the assert would trigger an abort and this point won't be reached)
  }

[jeetee]

The Q_ASSERT was there more as a glorified debug breakpoint; the further handling of the scenario is the same whether the assert would've been hit or not.

[jeetee]

ty!