fix: guard against wait utils without callback (#161)

Author: jrparish

lib/node-utils.ts

@@ -104,5 +104,5 @@ export function hasThenProperty(node: TSESTree.Node) {
 }
 
 export function isArrowFunctionExpression(node: TSESTree.Node): node is TSESTree.ArrowFunctionExpression {
-  return node.type === 'ArrowFunctionExpression'
+  return node && node.type === 'ArrowFunctionExpression'
 }

tests/lib/rules/prefer-find-by.test.ts

@@ -51,7 +51,13 @@ ruleTester.run(RULE_NAME, rule, {
       code: `
         await waitFor(() => expect(${queryMethod}('baz')).toBeInTheDocument());
       `
-    }))
+    })),
+    {
+      code: `
+        await waitFor();
+        await wait();
+      `
+    }
   ],
   invalid: [
     // using reduce + concat 'cause flatMap is not available in node10.x