Fix the description

Author: Linyxus

Diff for: compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -3706,15 +3706,15 @@ object Parsers {
           in.languageImportContext = in.languageImportContext.importContext(imp, NoSymbol)
           for case ImportSelector(id @ Ident(imported), EmptyTree, _) <- selectors do
             if Feature.handleGlobalLanguageImport(prefix, imported) && !outermost then
-              val location =
+              val desc =
                 if ctx.mode.is(Mode.Interactive) then
-                  "in the REPL"
-                else "at the toplevel"
+                  "not allowed in the REPL"
+                else "only allowed at the toplevel"
               val hint =
                 if ctx.mode.is(Mode.Interactive) then
                   f"\nTo use this language feature, include the flag `-language:$prefix.$imported` when starting the REPL"
                 else ""
-              syntaxError(em"this language import is only allowed $location$hint", id.span)
+              syntaxError(em"this language import is $desc$hint", id.span)
             if allSourceVersionNames.contains(imported) && prefix.isEmpty then
               if !outermost then
                 syntaxError(em"source version import is only allowed at the toplevel", id.span)