[FIR] Fix binding return expression to function

compiler/fir/lightTree/src/org/jetbrains/kotlin/fir/lightTree/converter/DeclarationsConverter.kt

@@ -1037,7 +1037,7 @@ class DeclarationsConverter(
         val parentNode = functionDeclaration.getParent()
         val isLocal = !(parentNode?.tokenType == KT_FILE || parentNode?.tokenType == CLASS_BODY)
         val firFunction = if (identifier == null) {
-            FirAnonymousFunctionImpl(null, session, returnType!!, receiverType, FirAnonymousFunctionSymbol())
+            FirAnonymousFunctionImpl(null, session, returnType!!, receiverType, FirAnonymousFunctionSymbol(), isLambda = false)
         } else {
             val functionName = identifier.nameAsSafeName()
             val status = FirDeclarationStatusImpl(

compiler/fir/lightTree/src/org/jetbrains/kotlin/fir/lightTree/converter/ExpressionsConverter.kt

@@ -127,7 +127,7 @@ class ExpressionsConverter(
             }
         }
 
-        return FirAnonymousFunctionImpl(null, session, implicitType, implicitType, FirAnonymousFunctionSymbol()).apply {
+        return FirAnonymousFunctionImpl(null, session, implicitType, implicitType, FirAnonymousFunctionSymbol(), isLambda = true).apply {
             context.firFunctions += this
             var destructuringBlock: FirExpression? = null
             for (valueParameter in valueParameterList) {