realm_emoji: Cleanup an unreachable try/except block.

Fixes: #3515.

tools/lint-all

@@ -373,7 +373,6 @@ def build_custom_checkers(by_lang):
              ('zerver/views/streams.py', 'return json_error(property_conversion)'),
              ('zerver/views/streams.py', 'return json_error(e.error, data=result, status=404)'),
              # We can't do anything about this.
-             ('zerver/views/realm_emoji.py', 'return json_error(e.messages[0])'),
              ('zerver/views/realm_filters.py', 'return json_error(e.messages[0], data={"errors": dict(e)})'),
          ]),
          'description': 'Argument to json_error should a literal string enclosed by _()'},

zerver/views/realm_emoji.py

@@ -1,14 +1,13 @@
 from __future__ import absolute_import
 
 from django.http import HttpRequest, HttpResponse
-from django.core.exceptions import ValidationError
 from django.utils.translation import ugettext as _
 from typing import Text
 
 from zerver.models import UserProfile
 from zerver.lib.emoji import check_emoji_admin, check_valid_emoji_name, check_valid_emoji
 from zerver.lib.request import JsonableError, REQ, has_request_variables
-from zerver.lib.response import json_success, json_error
+from zerver.lib.response import json_success
 from zerver.lib.actions import check_add_realm_emoji, do_remove_realm_emoji
 
 def list_emoji(request, user_profile):
@@ -23,10 +22,7 @@ def upload_emoji(request, user_profile, emoji_name=None, url=REQ()):
     # type: (HttpRequest, UserProfile, Text, Text) -> HttpResponse
     check_valid_emoji_name(emoji_name)
     check_emoji_admin(user_profile)
-    try:
-        check_add_realm_emoji(user_profile.realm, emoji_name, url, author=user_profile)
-    except ValidationError as e:
-        return json_error(e.messages[0])
+    check_add_realm_emoji(user_profile.realm, emoji_name, url, author=user_profile)
     return json_success()
 
 def delete_emoji(request, user_profile, emoji_name):