[NI] Remove lambda coersion to Unit in case of error return type(s)

Coersion to Unit from error type leads to misleading type mismatches:
"expected <expected lambda return type> found Unit", despite no user-provided Unit / empty lambda.
These diagnostics were collected, but not reported before, and that had been disguising the issue for a while.

KT-34729 Fixed

compiler/testData/diagnostics/tests/inference/regressions/kt2841_it.kt

@@ -1,3 +1,5 @@
+// !WITH_NEW_INFERENCE
+
 package a
 
 interface Closeable {
@@ -11,7 +13,7 @@ public inline fun <T: Closeable, R> T.use(block: (t: T)-> R) : R {
 }
 
 fun test() {
-    C().use {
+    C().<!NI;NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>use<!> {
         it.close()
         <!UNRESOLVED_REFERENCE!>x<!>
     }