[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.fir.kt

@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline fun<T> foo(block: () -> T):T = block()
+
+fun baz() {
+    val x: String = foo {
+        val task: String? = null
+        if (task == null) {
+            return
+        } else task
+    }
+}