Add isEmpty doc.

Author: kdquistanchala

packages/native/src/lib/ToBeEmptyElementAssertion.ts

@@ -40,7 +40,7 @@ export class ToBeEmptyElementAssertion extends Assertion<ReactTestInstance> {
     });
 
     return this.execute({
-      assertWhen: isEmpty(this.actual),
+      assertWhen: isEmpty(this.actual.children),
       error,
       invertedError,
     });

packages/native/src/lib/helpers/helpers.ts

@@ -14,15 +14,19 @@ export function instanceToString(instance: ReactTestInstance | null): string {
     return `<${instance.type.toString()} ... />`;
 }
 
-export function isEmpty(element: ReactTestInstance): boolean {
-  const children = element?.children;
-
-  if (!children) {
+/**
+ * Checks if a value is empty.
+ *
+ * @param value - The value to check.
+ * @returns `true` if the value is empty, `false` otherwise.
+ */
+export function isEmpty(value: unknown): boolean {
+  if (!value) {
     return true;
   }
 
-  if (Array.isArray(children)) {
-    return children.length === 0;
+  if (Array.isArray(value)) {
+    return value.length === 0;
   }
 
   return false;