onerror = function (message, exception) {
                if (scene) {
                    scene._removePendingData(texture);
                }
                if (onLoadObserver) {
                    texture.onLoadedObservable.remove(onLoadObserver);
                }
                // fallback for when compressed file not found to try again.  For instance, etc1 does not have an alpha capable type
                if (isKTX) {
                    _this.createTexture(urlArg, noMipmap, invertY, scene, samplingMode, null, onError, buffer, texture);
                }
                else if (BABYLON.Tools.UseFallbackTexture) {
                    _this.createTexture(BABYLON.Tools.fallbackTexture, noMipmap, invertY, scene, samplingMode, null, onError, buffer, texture);
                }
                if (onError) {
                    onError(message || "Unknown error", exception);
                }
            }
Usually called from BABYLON.Texture.ts.  Passed information to create a WebGLTexture.
@param {string} urlArg- This contains one of the following:
                        1. A conventional http URL, e.g. 'http://...' or 'file://...'
                        2. A base64 string of in-line texture data, e.g. 'data:image/jpg;base64,/...'
                        3. An indicator that data being passed using the buffer parameter, e.g. 'data:mytexture.jpg'

@param {boolean} noMipmap- When true, no mipmaps shall be generated.  Ignored for compressed textures.  They must be in the file.
@param {boolean} invertY- When true, image is flipped when loaded.  You probably want true. Ignored for compressed textures.  Must be flipped in the file.
@param {Scene} scene- Needed for loading to the correct scene.
@param {number} samplingMode- Mode with should be used sample / access the texture.  Default: TRILINEAR
@param {callback} onLoad- Optional callback to be called upon successful completion.
@param {callback} onError- Optional callback to be called upon failure.
@param {ArrayBuffer | HTMLImageElement} buffer- A source of a file previously fetched as either an ArrayBuffer (compressed or image format) or HTMLImageElement (image format)
@param {WebGLTexture} fallback- An internal argument in case the function must be called again, due to etc1 not having alpha capabilities.
@param {number} format-  Internal format.  Default: RGB when extension is '.jpg' else RGBA.  Ignored for compressed textures.

@returns {WebGLTexture} for assignment back into BABYLON.Texture