debug assert "num <= kMaxNumberOfDecks" in PlayerManager::slotChangeNumDecks on changing nanoKontrol2 mapping from custom to built-in

[mxmilkiib]

Bug Description

coredump; https://nxtcld.thingsandstuff.org/s/CdiMwZE3AprJWjG

I had both plugged in when I started Mixxx.

I go into the nanoKontrol2 controller config page, change from my "kn" preset to the official one in the drop-down, hit apply, there is several seconds pause then a crash.

Version

r8934-1

OS

Arch

[mxmilkiib]

Happens also if it's the only controller.

DEBUG ASSERT: "num <= kMaxNumberOfDecks" in function void PlayerManager::slotChangeNumDecks(double) at /home/milk/pkgs/mixxx-git-debug/src/mixxx-git/src/mixer/playermanager.cpp:307

Edit: also happens when I try to set my Reloop controller to use the nanoKontrol2 preset.

[ronso0]

What happens if you select None, restart and select the official mapping?

[mxmilkiib]

Lol, I get a #11678 segfault on closing mixxx.

On trying to switch from none to the official mapping, I get the same playermanager.cpp:307 crash.

[ronso0]

For some reason the official mapping tries to enable 8 decks by setting [App],num_decks. Max is 4.

mixxx/res/controllers/Korg-nanoKONTROL-2-scripts.js

Lines 62 to 64 in 3223a75

	NK2.init = function init() { // called when the device is opened & set up
	if (NK2.debug>2){print("##function: "+NK2.getFunctionName())};
	engine.setValue("[App]", "num_decks", NK2.numDecks);

In release builds this is ignored, and you hit this debug assert because you built Mixxx with cmake build option DEBUG_ASSERTIONS_FATAL = ON

For now, just set NK2.numDecks in the script header to 4 (or disable DEBUG_ASSERTIONS_FATAL if you don't need it).
Someone just needs to fix the (undocumented) nanoKontrol2 mapping.

[ronso0]

@mxmilkiib #12322 has been merged into 2.4, the built-in mapping should not thrown an error anymore.