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

compiler/testData/diagnostics/tests/sealed/WhenOnEmptySealed.fir.kt

@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+sealed class Sealed {
+
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        // We do not return anything, so else branch must be here
+    }
+}
+