Fix tiny compilation issue

dist/preview release/babylon.max.js

@@ -33285,6 +33285,9 @@ var BABYLON;
             }
             this._texture = texture;
             var callback = function (text) {
+                if (typeof text !== "string") {
+                    return;
+                }
                 var data = null;
                 var tempData = null;
                 var line;

src/Behaviors/Cameras/babylon.bouncingBehavior.ts

@@ -77,7 +77,7 @@ module BABYLON {
         // Connection
         private _attachedCamera: Nullable<ArcRotateCamera>;
 		private _onAfterCheckInputsObserver: Nullable<Observer<Camera>>;	
-		private _onMeshTargetChangedObserver: Nullable<Observer<AbstractMesh>>;
+		private _onMeshTargetChangedObserver: Nullable<Observer<Nullable<AbstractMesh>>>;
 
 		public init(): void {
 			// Do notihng

src/Behaviors/Cameras/babylon.framingBehavior.ts

@@ -142,7 +142,7 @@ module BABYLON {
         // Default behavior functions
         private _onPrePointerObservableObserver: Nullable<Observer<PointerInfoPre>>;
 		private _onAfterCheckInputsObserver: Nullable<Observer<Camera>>;
-		private _onMeshTargetChangedObserver: Nullable<Observer<AbstractMesh>>;
+		private _onMeshTargetChangedObserver: Nullable<Observer<Nullable<AbstractMesh>>>;
         private _attachedCamera: Nullable<ArcRotateCamera>;
         private _isPointerDown = false;
 		private _lastInteractionTime = -Infinity;

src/Materials/Textures/babylon.colorGradingTexture.ts

@@ -96,7 +96,7 @@ module BABYLON {
                 var tempData: Nullable<Float32Array> = null;
 
                 var line: string;
-                var lines = (<string>text).split('\n');
+                var lines = text.split('\n');
                 var size = 0, pixelIndexW = 0, pixelIndexH = 0, pixelIndexSlice = 0;
                 var maxColor = 0;