Renderer: Improve texture check in `_getShadowNodes()` (#33845)

src/renderers/common/Renderer.js

@@ -3341,7 +3341,7 @@ class Renderer {
 
 		if ( cache === undefined || cache.version !== version ) {
 
-			const hasMap = material.map !== null;
+			const hasMap = material.map && material.map.isTexture;
 			const hasColorNode = material.colorNode && material.colorNode.isNode;
 			const hasCastShadowNode = material.castShadowNode && material.castShadowNode.isNode;
 			const hasMaskNode = ( material.maskShadowNode && material.maskShadowNode.isNode ) || ( material.maskNode && material.maskNode.isNode );