Add regression test

tests/cases/compiler/getParameterNameAtPosition.ts

@@ -0,0 +1,11 @@
+// @strict: true
+
+// Repro from #30171
+
+interface Mock<Y extends any[]> extends Function {
+    (...args: Y): any;
+}
+type Tester = (opts: any, done: (...args: any[]) => any) => any;
+declare function cases(tester: Tester): void;
+declare function fn<Y extends any[]>(implementation?: (...args: Y) => any): Mock<Y>;
+cases(fn(opts => { }));