Add regression test

ahejlsberg · ahejlsberg · commit 0e446fe8c2b1 · 2018-03-28T13:16:29.000-07:00
diff --git a/tests/cases/conformance/types/conditional/conditionalTypes1.ts b/tests/cases/conformance/types/conditional/conditionalTypes1.ts
@@ -215,6 +215,10 @@ type T50 = IsNever<never>;  // true
 type T51 = IsNever<number>;  // false
 type T52 = IsNever<any>;  // false
 
+function f22<T>(x: T extends (infer U)[] ? U[] : never) {
+    let e = x[0];  // {}
+}
+
 // Repros from #21664
 
 type Eq<T, U> = T extends U ? U extends T ? true : false : false;
