Fix collada loader bug, which tried to access non-existing textures. Found by Sylence.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@3416 dfc29bdd-3216-0410-991c-e03cc46cb475

source/Irrlicht/CColladaFileLoader.cpp

@@ -1568,7 +1568,8 @@ const SColladaMaterial* CColladaFileLoader::findMaterial(const core::stringc& ma
 		{
 			// found the effect, instantiate by copying into the material
 			Materials[mat].Mat = Effects[effect].Mat;
-			Materials[mat].Mat.setTexture(0, getTextureFromImage(Effects[effect].Textures[0]));
+			if (Effects[effect].Textures.size())
+				Materials[mat].Mat.setTexture(0, getTextureFromImage(Effects[effect].Textures[0]));
 			Materials[mat].Transparency = Effects[effect].Transparency;
 			// and indicate the material is instantiated by removing the effect ref
 			Materials[mat].InstanceEffectId = "";