[minor] updating fir testdata

compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitution.fir.kt

@@ -20,3 +20,18 @@ fun buildB() {
     B.Builder().<!UNRESOLVED_REFERENCE!>a2<!>()
     B.Builder().<!UNRESOLVED_REFERENCE!>a3<!>()
 }
+
+// additional example from #KT-34820
+
+class R
+class P
+
+typealias F = R.(P) -> Unit
+
+fun guess(): F? = TODO()
+fun consume(f: F) {}
+
+fun problem() {
+    val p = guess()
+    consume(p ?: {})
+}