diff --git a/packages/hydrooj/src/error.ts b/packages/hydrooj/src/error.ts
index 96945e63..198a4495 100644
--- a/packages/hydrooj/src/error.ts
+++ b/packages/hydrooj/src/error.ts
@@ -107,8 +107,8 @@ export const FileExistsError = Err('FileExistsError', ForbiddenError, 'File {0}
 export const HackFailedError = Err('HackFailedError', ForbiddenError, 'Hack failed: {0}');
 export const ProblemAlreadyExistError = Err('ProblemAlreadyExistError', ForbiddenError, 'Problem {0} already exists.');
 export const ProblemAlreadyUsedByContestError = Err('ProblemAlreadyUsedByContestError', ForbiddenError, 'Problem {0} is already used by contest {1}.');
-export const ProblemNotAllowPretestError = Err('ProblemNotAllowPretestError', ForbiddenError, 'This {0} is not allow run pretest.');
-export const ProblemNotAllowLanguageError = Err('ProblemNotAllowSubmitError', ForbiddenError, 'This language is not allow to submit.');
+export const ProblemNotAllowPretestError = Err('ProblemNotAllowPretestError', ForbiddenError, 'Pretesting is not supported for {0}.');
+export const ProblemNotAllowLanguageError = Err('ProblemNotAllowSubmitError', ForbiddenError, 'This language is not allowed to submit.');
 
 export const HackRejudgeFailedError = Err('HackRejudgeFailedError', BadRequestError, 'Cannot rejudge a hack record.');
 export const CannotDeleteSystemDomainError = Err('CannotDeleteSystemDomainError', BadRequestError, 'You are not allowed to delete system domain.');
diff --git a/packages/ui-default/utils/index.ts b/packages/ui-default/utils/index.ts
index 762d37a1..6107c345 100644
--- a/packages/ui-default/utils/index.ts
+++ b/packages/ui-default/utils/index.ts
@@ -32,7 +32,7 @@ export function getAvailableLangs(langsList?: string[]) {
   const Langs = {};
   for (const key in window.LANGS) {
     if (prefixes.has(key)) continue;
-    if (langsList && langsList.length && langsList.join('') && !langsList.includes(key)) continue;
+    if ((langsList instanceof Array) && !langsList.includes(key)) continue;
     if (window.LANGS[key].hidden && !langsList?.includes(key)) continue;
     if (window.LANGS[key].disabled) continue;
     Langs[key] = window.LANGS[key];