Program: 58400
Project: 58400
Buggy source:
@SubscribeEvent public void tickStart(PlayerTickEvent evt){
  if (evt.phase != Phase.START) {
    return;
  }
  if (MinecraftServer.getServer() != null) {
    if (!MinecraftServer.getServer().getConfigurationManager().func_152596_g(evt.player.getGameProfile())) {
      return;
    }
  }
  if (lastPoll > 0) {
    --lastPoll;
    return;
  }
  lastPoll=400;
  if (!_notificationDisplayed && _updateThread.checkComplete()) {
    _notificationDisplayed=true;
    FMLCommonHandler.instance().bus().unregister(this);
    if (_updateThread.newVersionAvailable()) {
      if (!CoFHProps.enableUpdateNotice && !_updateThread.isCriticalUpdate()) {
        return;
      }
      ModVersion newVersion=_updateThread.newVersion();
      EntityPlayer player=evt.player;
      IChatComponent chat=new ChatComponentText("String_Node_Str");
{
        ChatStyle data=modname.createShallowCopy();
        IChatComponent msg=new ChatComponentText(newVersion.modVersion().toString()).setChatStyle(version);
        data.setChatHoverEvent(new HoverEvent(HoverEvent.Action.SHOW_TEXT,msg));
        chat.appendSibling(new ChatComponentText("String_Node_Str" + _mod.getModName() + "String_Node_Str").setChatStyle(data));
      }
      chat.appendSibling(new ChatComponentTranslation("String_Node_Str").setChatStyle(white));
      chat.appendText(GOLD + "String_Node_Str");
      player.addChatMessage(chat);
      chat=new ChatComponentText("String_Node_Str");
      if (!Strings.isNullOrEmpty(_downloadUrl)) {
        chat.appendText(WHITE + "String_Node_Str");
        ChatStyle data=download.createShallowCopy();
        data.setChatClickEvent(new ClickEvent(ClickEvent.Action.OPEN_URL,_downloadUrl));
        chat.appendSibling(new ChatComponentTranslation("String_Node_Str").setChatStyle(data));
        chat.appendText(WHITE + "String_Node_Str");
      }
      chat.appendSibling(new ChatComponentText(newVersion.description()).setChatStyle(description));
      player.addChatMessage(chat);
    }
  }
}

Fixed version (ground truth):
@SubscribeEvent public void tickStart(PlayerTickEvent evt){
  if (evt.phase != Phase.START) {
    return;
  }
  if (MinecraftServer.getServer() != null && MinecraftServer.getServer().isServerRunning()) {
    if (!MinecraftServer.getServer().getConfigurationManager().func_152596_g(evt.player.getGameProfile())) {
      return;
    }
  }
  if (lastPoll > 0) {
    --lastPoll;
    return;
  }
  lastPoll=400;
  if (!_notificationDisplayed && _updateThread.checkComplete()) {
    _notificationDisplayed=true;
    FMLCommonHandler.instance().bus().unregister(this);
    if (_updateThread.newVersionAvailable()) {
      if (!CoFHProps.enableUpdateNotice && !_updateThread.isCriticalUpdate()) {
        return;
      }
      ModVersion newVersion=_updateThread.newVersion();
      EntityPlayer player=evt.player;
      IChatComponent chat=new ChatComponentText("String_Node_Str");
{
        ChatStyle data=modname.createShallowCopy();
        IChatComponent msg=new ChatComponentText(newVersion.modVersion().toString()).setChatStyle(version);
        data.setChatHoverEvent(new HoverEvent(HoverEvent.Action.SHOW_TEXT,msg));
        chat.appendSibling(new ChatComponentText("String_Node_Str" + _mod.getModName() + "String_Node_Str").setChatStyle(data));
      }
      chat.appendSibling(new ChatComponentTranslation("String_Node_Str").setChatStyle(white));
      chat.appendText(GOLD + "String_Node_Str");
      player.addChatMessage(chat);
      chat=new ChatComponentText("String_Node_Str");
      if (!Strings.isNullOrEmpty(_downloadUrl)) {
        chat.appendText(WHITE + "String_Node_Str");
        ChatStyle data=download.createShallowCopy();
        data.setChatClickEvent(new ClickEvent(ClickEvent.Action.OPEN_URL,_downloadUrl));
        chat.appendSibling(new ChatComponentTranslation("String_Node_Str").setChatStyle(data));
        chat.appendText(WHITE + "String_Node_Str");
      }
      chat.appendSibling(new ChatComponentText(newVersion.description()).setChatStyle(description));
      player.addChatMessage(chat);
    }
  }
}