[FIR] Report missing ASSIGNMENT_TYPE_MISMATCH on functional types

^KT-45989

compiler/testData/diagnostics/tests/inference/lambdaInValInitializerWithAnonymousFunctions.fir.kt

@@ -5,5 +5,5 @@ val test2f: suspend Any.() -> Unit = fun Any.() {}
 
 // This is a bug in the old inference and should be fixed in new inference
 // see "Fix anonymous function literals handling in type checker" for more details
-val test3f: suspend Any.(Int) -> Int = fun (k: Int) = k + 1
-val test4f: SuspendFn = fun Any.() {}
+val test3f: suspend Any.(Int) -> Int = <!INITIALIZER_TYPE_MISMATCH!>fun (k: Int) = k + 1<!>
+val test4f: SuspendFn = <!INITIALIZER_TYPE_MISMATCH!>fun Any.() {}<!>