CTD for NULL group members in mqnext branch

mqnext doesn't check for null parameters in GetDistance(), so when using AddSpawn() in MQ2WorstHurt, for mqnext it will CTD if a group member is NULL.

Inserting a check before the AddSpawn() call will prevent it, e.g.:

  // Add group members if set to, and we're in a group
  if (includeGroup && pChar && pChar->pGroupInfo)
  {
    for (CGroupMember* pMember : *pChar->pGroupInfo)
    {
      if (pMember && pMember->pSpawn)
        AddSpawn(pMember->pSpawn);
    }
  }

Currently, with the || in that call, it will evaluate both conditions and crash on NULL.

  auto AddSpawn = [&](PSPAWNINFO pSpawn) -> void {
    // Ignore spawns if they are null, outside our radius, or they're not a PC/Pet
    if (!pSpawn || GetDistance(pCharSpawn, pSpawn) > radius)
      return;