[rust-compiler] Dedup async-reassignment immutability diagnostic

compiler/crates/react_compiler_validation/src/validate_locals_not_reassigned_after_render.rs

@@ -158,6 +158,7 @@ fn get_context_reassignment(
                                 }),
                             );
                             // Return null (don't propagate further) — matches TS behavior
+                            return None;
                         } else {
                             // Propagate reassignment info on the lvalue
                             reassigning_functions

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-multiple-async-callbacks.expect.md

@@ -0,0 +1,38 @@
+
+## Input
+
+```javascript
+function Component() {
+	let value: number | undefined;
+	const a = async () => {
+		value = 1;
+	};
+	const b = async () => {
+		value = 2;
+	};
+	return <div>{[a, b]}</div>;
+}
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Cannot reassign variable in async function
+
+Reassigning a variable in an async function can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.invalid-reassign-local-variable-in-multiple-async-callbacks.ts:4:2
+  2 | 	let value: number | undefined;
+  3 | 	const a = async () => {
+> 4 | 		value = 1;
+    | 		^^^^^ Cannot reassign `value`
+  5 | 	};
+  6 | 	const b = async () => {
+  7 | 		value = 2;
+```
+
+

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-multiple-async-callbacks.tsx

@@ -0,0 +1,10 @@
+function Component() {
+	let value: number | undefined;
+	const a = async () => {
+		value = 1;
+	};
+	const b = async () => {
+		value = 2;
+	};
+	return <div>{[a, b]}</div>;
+}