FIR initializer: don't report type mismatch on incompatible extensions

This commit suppresses type mismatch error from KT-45989

compiler/testData/diagnostics/tests/inference/completion/postponedArgumentsAnalysis/basic.fir.kt

@@ -153,7 +153,7 @@ fun main() {
     // Convert to extension lambda is impossible because the lambda parameter types aren't specified explicitly
     select(id(fun String.(x: String) {}), id(fun(x: String, y: String) { }), { x, y -> x })
     select(id(id(fun(x: String, y: String) { }), <!TOO_MANY_ARGUMENTS!>fun String.(x: String) {}<!>), { x, y -> x })
-    val x26: Int.(String) -> Int = <!INITIALIZER_TYPE_MISMATCH!>fun (x: String) = 10<!> // it must be error, see KT-38439
+    val x26: Int.(String) -> Int = fun (x: String) = 10 // it must be error, see KT-38439
     // Receiver must be specified in anonymous function declaration
     val x27: Int.(String) -> Int = id(fun (x: String) = 10)
     select(id<Int.(String) -> Unit> {}, { x: Int, y: String -> x })