Update ExpressionResultTest.php

Author: staabm

tests/PHPStan/Analyser/ExpressionResultTest.php

@@ -81,6 +81,10 @@ public static function dataIsAlwaysTerminating(): array
 				'fn() => yield (exit());',
 				false,
 			],
+			[
+				'(fn() => exit())();', // immediately invoked function expression
+				true,
+			],
 			[
 				'@exit();',
 				true,