Go to mods/fleaden/data/config/exerelinFactionConfig/fleaden.json
Go to:
"miningVariantsOrWings":["maqiubiqiu_zhiyuan", "mining_drone_wing"]
And add a "," at the end.
IMPORTANT NOTE: if you are using Notepad (the normal Windows version) then move the cursor just before the "]" THEN press the Right Arrow Key and THEN insert the ",".
The reason for this is that Notepad is a bit screwy with how it visualizes certain formats and linebreaks if you try to do it from the rightmost side of the "]" then you might accidentally put the "," after the linebreak instead of after the "]", you can see this by using the arrow keys, you'll notice that after the "]" you have to press right two times in order to move the cursor by another space.
Or you can just use Word or Notepad++