also exclude potentially undefined methods from WritableKeys<T>

Author: zefir-git

src/BaseComponent.ts

@@ -25,7 +25,7 @@ type WritableKeys<T> = {
             ) ? true : false
         ) extends false
         ? never
-        : (T[Prop] extends Function | null ? never : Prop);
+        : (T[Prop] extends Function | null | undefined ? never : Prop);
 }[keyof T];