fix(prefer-expect-resolves): don't crash on expect chain without a value (#2002)

Author: G-Rath

src/rules/__tests__/prefer-expect-resolves.test.ts

@@ -12,6 +12,11 @@ const ruleTester = new RuleTester({
 ruleTester.run('prefer-expect-resolves', rule, {
   valid: [
     'expect.hasAssertions()',
+    dedent`
+      it('passes', async () => {
+        await expect().resolves.toBe(true);
+      });
+    `,
     dedent`
       it('passes', async () => {
         await expect(someValue()).resolves.toBe(true);

src/rules/prefer-expect-resolves.ts

@@ -32,7 +32,7 @@ export default createRule({
 
       const [awaitNode] = parent.arguments;
 
-      if (awaitNode.type === AST_NODE_TYPES.AwaitExpression) {
+      if (awaitNode?.type === AST_NODE_TYPES.AwaitExpression) {
         context.report({
           node: awaitNode,
           messageId: 'expectResolves',