The error is back with the following code: 
if (command === "accept") {
    if (argsresult === "group") {
      if (groupSteamID === "") {
        message.channel.sendMessage("No group invite to accept!");
        return;
      } else {
        sclient.respondToGroupInvite.accept(groupSteamID) = true;
        message.channel.sendMessage("Accepted group invite: " + friendrqst);
        console.log("Accepted group invite: " + friendrqst);
      }
    }
  }
  if (command === "decline") {
    if (argsresult === "group") {
      if (groupSteamID === "") {
        message.channel.sendMessage("No group invite to decline!");
        return; 
      } else {
        sclient.accept(groupSteamID) = false;
        message.channel.sendMessage("Declined group invite: " + groupSteamID);
        console.log("Declined group invite: " + groupSteamID);
      }
    }
  }
I tried the accept and decline command(sclient.accept and sclient.respondToGroupInvite.accept) Both give me the error that its no function 
sclient.on('groupRelationship', (steamid, relationship) => {
  groupSteamID = steamid;
  
  if(relationship === 2) {
    dbot.channels.get('302817074269519873').sendMessage('You have been invited to this group: "' + groupSteamID + '" \n If you want to accept the group request, reply with ``!accept group``. \n And if you want to decline it, reply with ``!decline group``.');
    console.log('New group invite to this group: "' + groupSteamID + '"');
  }
});