Scripting: fix script type extraction on psi2ir

#KT-48812 fixed

libraries/tools/kotlin-main-kts-test/testData/kt48812.main.kts

@@ -0,0 +1,11 @@
+@file:DependsOn("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.2")
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.runBlocking
+
+fun printInt(n : Int) = println(n)
+
+runBlocking {
+    flowOf(1, 2, 3)
+        .onEach(::printInt)
+        .collect()
+}