textures: check if the main loop is runing before loading texture

[gucio321]

this should clearify the panic, that appears when user tries to load texture befor calling (*MasterWindow).Run

[gucio321]

@AllenDang maybe we can also add QueueNewTextureFromRgba or something that allows user to call texture-loading stuff in main function / out of game loop? the reason is that loading texture in app-loop is a bit complicated and annoying, beacuse we need to check if the texture isn't already loaded

[codecov-commenter]

Codecov Report

Merging #451 (eab3d00) into master (5af165b) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##           master    #451      +/-   ##
=========================================
- Coverage    2.91%   2.90%   -0.02%     
=========================================
  Files          30      30              
  Lines        3123    3136      +13     
=========================================
  Hits           91      91              
- Misses       3032    3045      +13     

Impacted Files	Coverage Δ
Context.go	80.64% <ø> (ø)
MasterWindow.go	0.00% <0.00%> (ø)
Texture.go	0.00% <0.00%> (ø)

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[gucio321]

well, it should work now. @AllenDang is this inside of Run loop ok? IMO it shouldn't decrease performence or sth...

[gucio321]

or better call this texture-queue processing stuff once an lock EnqueueNewTextureFromRgba after Run() call... 🤔