Warning about controller_input_active in the log

[Christian]

When Mixxx is started with a MIDI controller attached whose mapping uses a `components.EffectUnit`, the log contains following warning:

```
Warning [Controller]: ControlDoublePrivate::getControl returning NULL for ( "[EffectRack1_EffectUnit1]" , "controller_input_active" )
```

The key `controller_input_active` is used in only [3 files](https://github.com/mixxxdj/mixxx/search?q=controller_input_active):

- [`effectchainslot.cpp`](https://github.com/mixxxdj/mixxx/blob/5b85c75fb6906204ae882f9153372537654857bf/src/effects/effectchainslot.cpp#L95)
- `midi-components-0.0.js`: [L761](https://github.com/mixxxdj/mixxx/blob/010ea3315efabf85550607ef8cddcc4ecefcbe1b/res/controllers/midi-components-0.0.js#L761), [L775](https://github.com/mixxxdj/mixxx/blob/010ea3315efabf85550607ef8cddcc4ecefcbe1b/res/controllers/midi-components-0.0.js#L775)
- [`res/skins/LateNight/fx/singletons.xml`](https://github.com/mixxxdj/mixxx/blob/ca87f6a1c82f0a42263efd0019025cec92ee030b/res/skins/LateNight/fx/singletons.xml#L61)

I suppose that the `EffectChainSlot` object might be created after initialization of the controller mapping, which seems to be too late.

[Be (be.ing)]

The initialization of the effects system is a tangled web of spaghetti and I caution anyone against touching it before https://github.com/mixxxdj/mixxx/pull/2618 is merged.

[ronso0 (ronso0)]

I thought errors like this were recently fixed by https://github.com/mixxxdj/mixxx/pull/3329 ?
@Chirstian Can you try again with a recent 2.3 build?

[Christian (ubuntu-linux-user)]

I cannot reproduce the problem on Ubuntu Focal using the build from `ppa:mixxx/mixxxbetas` (2.3 r7808).

I can reproduce the problem on Windows using build 2.2.4 (2.2 r6798) with the controller directory of branch 2.3.

I'd like to check 2.3 on Windows, too, but I don't want to touch my stable installation. Is it possible to install 2.2 and 2.3 in parallel on Windows?

[Jan Holthuis (holthuis-jan)]

I'm pretty sure I fixed that issue in https://github.com/mixxxdj/mixxx/pull/2948.

[Jan Holthuis (holthuis-jan)]

Ah, looks like that's in in fact a different bug.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/10228