I've had this issue with more than one plugin on load. I remember not having this issue a couple years ago and the main plugins like Discord Core started with the server. Then after one of the bigger updates it stopped doing it. Luckily I was able to find the plugin -Timed Execute- to start the plugins every server start. It still says the error you've been getting but later in startup it'll load timed execute that will run any plugins you have added into it's .json file. Anyways if you're still not sure what to do here's a link: Timed Execute
Also if it helps, these are my settings to start the plugins I have that stopped starting with the server. Under "TimerOnce". Numbers are in seconds.
{
"EnableInGameTime-Timer": false,
"EnableRealTime-Timer": false,
"EnableTimerOnce": true,
"EnableTimerRepeat": false,
"InGameTime-Timer": {
"01:00": "weather rain",
"12:00": "command 1",
"15:00": "command 2"
},
"RealTime-Timer": {
"16:00:00": "command1 arg",
"16:30:00": "command2 arg",
"17:00:00": "command3 arg",
"18:00:00": "command4 arg"
},
"TimerOnce": {
"oxide.load DiscordAuth": 1,
"oxide.load DiscordCore": 6,
"oxide.load Rustcord ": 11
},
"TimerRepeat": {
"command1 arg": 300,
"command2 'msg'": 300
}
}