tdf#88576 fix handling of empty arguments in IF(), IFERROR() and IFNA()

Change-Id: I8acca26cf7398768a9e25f97f3a9e61754ab2179
Reviewed-on: https://gerrit.libreoffice.org/14415Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>

sc/source/core/tool/interpr4.cxx

@@ -3028,6 +3028,9 @@ void ScInterpreter::ScExternal()
 
 void ScInterpreter::ScMissing()
 {
+    if ( aCode.IsEndOfPath() )
+        PushTempToken( new ScEmptyCellToken( false, false ) );
+    else
         PushTempToken( new FormulaMissingToken );
 }