Happened after selecting tree seeder and dragging over an area.

The mod Treez (Base Game) (1.20.5) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event treez-base-game::on_player_selected_area (ID 57)
tree-plant can not be part a entity ghost.
stack traceback:
[C]: in function 'create_entity'
treez-base-game/control/seeder.lua:96: in function <treez-base-game/control/seeder.lua:78>

Thank ya for the report. That should be fixed now.

Unfortunately I'm getting the same error on version 1.20.13 but the line number is different.

The mod Treez (Base Game) (1.20.13) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event treez-base-game::on_player_selected_area (ID 57)
tree-plant can not be part a entity ghost.
stack traceback:
[C]: in function 'create_entity'
treez-base-game/control/seeder.lua:116: in function <treez-base-game/control/seeder.lua:78>

Humm... What other mods are you running? Most importantly are you running space age?