Add missing error toast on presentation upload (#5034)

app/assets/locales/en.json

@@ -406,6 +406,7 @@
       "problem_completing_action": "The action can't be completed. \n Please try again.",
       "file_type_not_supported": "The file type is not supported.",
       "file_size_too_large": "The file size is too large.",
+      "file_upload_error": "The file can't be uploaded.",
       "signin_required": "You must be signed in to access this page.",
       "roles": {
         "role_assigned": "This role can't be deleted because it is assigned to at least one user."