K2: report empty intersection warnings from completion properly

compiler/testData/codegen/box/fir/emptyIntersectionWarning.kt

@@ -0,0 +1,13 @@
+// TARGET_BACKEND: JVM_IR
+// IGNORE_BACKEND_K1: JVM_IR
+
+interface I
+class View1
+
+fun <T : View1> findViewById1(): T? = null
+fun test1(): I? = findViewById1()
+
+fun box(): String {
+    test1()
+    return "OK"
+}