make sure effect chains are initialized properly

[Be-ing]

if effects.xml is a valid XML file but does not contain enough elements like this. That should never happen, but in case it does, this change will catch it.

[daschuer]

Thank you for this quick band aid.

It is still possible to create too many effects.

Did you consider decoupling slot creating and effect loading?
It looks wrong, that a file for storing effects is also responsible for setting up the slots including their Control Objects. Will it be a big change?

[Be-ing]

Putting more than 4 <EffectChain> elements in the XML file does not seem to have any negative impact.

Decoupling EffectChainSlot creation and loading state from XML would be a bit complicated. This works as is.

[daschuer]

Putting more than 4 elements in the XML file does not seem to have any negative impact.

I have not tested it yet, but I assume that there are additional effects are added to new effect slots created along with there Control Objects. We should avoid it to not give the impression that the number of effects slots can be set by the XML file.

If we need a dynamic number of effect slots, we should allow the skins to set them up not the effect.xml which is IMHO only responsible for the content of the effect slots.

[daschuer]

Decoupling EffectChainSlot creation and loading state from XML would be a bit complicated. This works as is.

It is OK to me to keep the current situation. To clarify, do you agree that it should be decoupled finally.
If yes, we should issue a bug for it.

[Be-ing]

It is OK to me to keep the current situation. To clarify, do you agree that it should be decoupled finally.
If yes, we should issue a bug for it.

I don't think it matters much either way. If you want to open a bug for it, go ahead.

[daschuer]

Thank you! LGTM

The bug is here:
https://bugs.launchpad.net/mixxx/+bug/1687320