ControlDoublePrivate: log warning before assert fails.

[daschuer]

Make sure the warning is printed before the assertion kills mixxx.
This should help to debug issues discussed here:

https://mixxx.zulipchat.com/#narrow/stream/247620-development-help/topic/qDebug.20messages.20with.20DEBUG_ASSERTIONS_FATAL

[daschuer]

@ronso0: This should help to find CO issues.

[coveralls]

Pull Request Test Coverage Report for Build 1153450206

• 3 of 11 (27.27%) changed or added relevant lines in 1 file are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.001%) to 25.962%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/control/control.cpp	3	11	27.27%

Files with Coverage Reduction	New Missed Lines	%
src/control/control.cpp	4	76.61%

Totals
Change from base Build 1152021735:	0.001%
Covered Lines:	20004
Relevant Lines:	77051

---

💛 - Coveralls

[Holzhaus]

The condition is out of sight here. Please use something like

Suggested change

	DEBUG_ASSERT(false);
	DEBUG_ASSERT(!"Tried to create Control Object that already exists.");

[Holzhaus]

Same here

[Holzhaus]

And here

[Holzhaus]

And here

[daschuer]

Done

[ronso0]

Thanks @daschuer

btw when testing with Shade it stopped here for [Channel3], end_of_track. I can not be trigger this reliably though it happened more often when one deck was playing in the track end region earlier.

mixxx/src/control/control.cpp

Lines 180 to 184 in 7bb2f29

	if (!flags.testFlag(ControlFlag::NoWarnIfMissing)) {
	qWarning() << "ControlDoublePrivate::getControl returning NULL for ("
	<< key.group << "," << key.item << ")";
	DEBUG_ASSERT(flags.testFlag(ControlFlag::NoAssertIfMissing));
	}

[Holzhaus]

LGTM, thank you.