Scripting: fix script type extraction on psi2ir

#KT-48812 fixed

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/descriptors/IrBasedDescriptors.kt

@@ -1181,6 +1181,13 @@ private fun makeKotlinType(
                 )
             }
         }
+        is IrScriptSymbol -> {
+            TypeUtils.makeUnsubstitutedType(
+                classifier.toIrBasedDescriptorIfPossible(),
+                MemberScope.Empty,
+                KotlinTypeFactory.EMPTY_REFINED_TYPE_FACTORY
+            ).makeNullableAsSpecified(hasQuestionMark)
+        }
         else -> error("unknown classifier kind $classifier")
     }
 
@@ -1200,3 +1207,8 @@ private fun IrSimpleFunctionSymbol.toIrBasedDescriptorIfPossible(): FunctionDesc
 @OptIn(ObsoleteDescriptorBasedAPI::class)
 private fun IrPropertySymbol.toIrBasedDescriptorIfPossible(): PropertyDescriptor =
     if (isBound) owner.toIrBasedDescriptor() else descriptor
+
+// this is a temporary solution for scripts - seems that introducing full-blown emulation of descriptors for the single degenerate case
+// doesn't make any sense.
+@OptIn(ObsoleteDescriptorBasedAPI::class)
+private fun IrScriptSymbol.toIrBasedDescriptorIfPossible(): ScriptDescriptor = descriptor

libraries/tools/kotlin-main-kts-test/test/org/jetbrains/kotlin/mainKts/test/mainKtsTest.kt

@@ -223,6 +223,12 @@ class MainKtsTest {
         assertEquals("success", value)
     }
 
+    @Test
+    fun testKt48812() {
+        val res = evalFile(File("$TEST_DATA_ROOT/kt48812.main.kts"))
+        assertSucceeded(res)
+    }
+
     private fun assertSucceeded(res: ResultWithDiagnostics<EvaluationResult>) {
         Assert.assertTrue(
             "test failed:\n  ${res.reports.joinToString("\n  ") { it.message + if (it.exception == null) "" else ": ${it.exception}" }}",

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()
+}