Fix Matrix3 Matrix4 getInverse throwOnDegenerate (#9405)

* Fix Matrix3 Matrix4 getInverse throwOnDegenerate

* Update throwOnDegenerate assertion

src/math/Matrix3.js

@@ -196,7 +196,7 @@ Matrix3.prototype = {
 
 			var msg = "THREE.Matrix3.getInverse(): can't invert matrix, determinant is 0";
 
-			if ( throwOnDegenerate || false ) {
+			if ( throwOnDegenerate === true ) {
 
 				throw new Error( msg );
 

src/math/Matrix4.js

@@ -625,7 +625,7 @@ Matrix4.prototype = {
 
 			var msg = "THREE.Matrix4.getInverse(): can't invert matrix, determinant is 0";
 
-			if ( throwOnDegenerate || false ) {
+			if ( throwOnDegenerate === true ) {
 
 				throw new Error( msg );