I got this error message when I tried to mine a teleporter beacon while I stood next to it, then I had to reload the savegame. I don't have any problems with other beacons.

Error while running event on_player_mined_item (ID 8)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
PersonalTeleporter/control.lua:466: in function 'removeTelFromList'
PersonalTeleporter/control.lua:459: in function 'updateTelporterList'
PersonalTeleporter/control.lua:423: in function <PersonalTeleporter/control.lua:421>

Edit: Error still occurs after disabling all other mods.
Edit2: When trying to rename the same beacon I got this error and a crash:

Error while running event on_gui_click (ID 1)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
PersonalTeleporter/control.lua:232: in function <PersonalTeleporter/control.lua:121>

so a few questions what version are you on of the mod and version of factorio. did you recently update the mod or have you ever updated the mod on the current play through. how long has this beacon been in place. is this the only beacon that is giving you problems. does the beacon work when you try to teleport to it. it might be easier if you message me directly on the old website (https://forums.factorio.com/viewtopic.php?f=93&t=24157).