Fixed pbr material serialization and fixed legacy pbr check in Material.ts

materialsLibrary/src/legacyPBR/babylon.legacyPBRMaterial.ts

@@ -1689,7 +1689,7 @@ module BABYLON {
 
         public serialize(): any {
             var serializationObject = SerializationHelper.Serialize(this);
-            serializationObject.customType = "BABYLON.legacyPBRMaterial";
+            serializationObject.customType = "BABYLON.LegacyPBRMaterial";
             return serializationObject;
         }
 

src/Materials/babylon.material.ts

@@ -589,8 +589,8 @@
             }
 
             if (parsedMaterial.customType === "BABYLON.PBRMaterial" && !parsedMaterial.overloadedAlbedo) {
-                parsedMaterial.customType === "BABYLON.legacyPBRMaterial";
-                if (!(<any>BABYLON).legacyPBRMaterial) {
+                parsedMaterial.customType = "BABYLON.LegacyPBRMaterial";
+                if (!(<any>BABYLON).LegacyPBRMaterial) {
                     BABYLON.Tools.Error("Your scene is trying to load a legacy version of the PBRMaterial, please, include it from the materials library.");
                     return;
                 }