Properly check for result when getting pipeline in Msaa

[BorisBoutillier]

Objective

• This aims to fix two_passes example breaking on Windows #11755
• After Async pipeline compilation #10812 some pipeline compilation can take more time than before and all call to get_render_pipeline should check the result.

Solution

• Check get_render_pipeline call result for msaa_writeback
• I checked that no other call to get_render_pipeline in bevy code base is missng the checking on the result.

[afonsolage]

Tested and is working fine!

Just a question: The problems seems to be caused by some ordering issue on async pipeline compilation, so guarding the PipelineCache won't hide the underlying issue?

I mean, returning Ok(()) will disable the msaa_writeback and fix the crash, but I'm missing something or this will sometimes enable msaa_writeback and sometimes not, depending on the order in which the async pipeline compilation ran?

[BorisBoutillier]

I mean, returning Ok(()) will disable the msaa_writeback and fix the crash, but I'm missing something or this will sometimes enable msaa_writeback and sometimes not, depending on the order in which the async pipeline compilation ran?

I am not a full rendering expert, but as far as I understand it, the pipeline only needs to be compiled once, but it can take time some time to compile and now that it is spawned, more than one frame ( the spawning itself can take some time, probably what happens with the example). After compilation, the pipeline will be run each frame, the protection prevent the pipeline to be run while its compilation is not yet finished.

So the first few frames of the example can have no msaa, but afterwards it will always be enabled.
I checked it with some printing, and effectively I can have up to ~10 frame without the pipeline ready, then it is always there.