[HOTFIX] Fix model loading when some material paths are null in loadFromUrl()
[HOTFIX] Fix model loading when some material paths are null in loadFromUrl()

sereepap2029/playcanvas,aidinabedi/playcanvas-engine,H1Gdev/engine,aidinabedi/playcanvas-engine,playcanvas/engine,sereepap2029/playcanvas,MicroWorldwide/PlayCanvas,MicroWorldwide/PlayCanvas,H1Gdev/engine,playcanvas/engine,guycalledfrank/engine,sereepap2029/playcanvas,guycalledfrank/engine