Updated builds.

build/three.js

@@ -4963,10 +4963,10 @@
 
 					var parameter_src = uniforms_src[ u ][ p ];
 
-					if ( parameter_src.isColor ||
+					if ( parameter_src && ( parameter_src.isColor ||
 						parameter_src.isMatrix3 || parameter_src.isMatrix4 ||
 						parameter_src.isVector2 || parameter_src.isVector3 || parameter_src.isVector4 ||
-						parameter_src.isTexture ) {
+						parameter_src.isTexture ) ) {
 
 						uniforms_dst[ u ][ p ] = parameter_src.clone();
 

build/three.modules.js

@@ -4957,10 +4957,10 @@ var UniformsUtils = {
 
 				var parameter_src = uniforms_src[ u ][ p ];
 
-				if ( parameter_src.isColor ||
+				if ( parameter_src && ( parameter_src.isColor ||
 					parameter_src.isMatrix3 || parameter_src.isMatrix4 ||
 					parameter_src.isVector2 || parameter_src.isVector3 || parameter_src.isVector4 ||
-					parameter_src.isTexture ) {
+					parameter_src.isTexture ) ) {
 
 					uniforms_dst[ u ][ p ] = parameter_src.clone();