Digging broken textline:lcd crash

[S-S-X]

2020-04-12 23:24:12: ERROR[Main]: ServerError: AsyncErr: ServerThread::run Lua: Runtime error from mod 'textline' in callback node_on_dig(): Runtime error from mod 'textline' in callback node_on_destruct(): /data/world//worldmods/textline/init.lua:46: attempt to index a nil value
2020-04-12 23:24:12: ERROR[Main]: stack traceback:
2020-04-12 23:24:12: ERROR[Main]: 	/data/world//worldmods/textline/init.lua:46: in function 'clearscreen'
2020-04-12 23:24:12: ERROR[Main]: 	/data/world//worldmods/textline/init.lua:116: in function </data/world//worldmods/textline/init.lua:115>
2020-04-12 23:24:12: ERROR[Main]: 	[C]: in function 'remove_node'
2020-04-12 23:24:12: ERROR[Main]: 	/usr/local/share/minetest/builtin/game/item.lua:621: in function </usr/local/share/minetest/builtin/game/item.lua:550>
2020-04-12 23:24:12: ERROR[Main]: stack traceback:
2020-04-12 23:24:12: ERROR[Main]: 	[C]: in function 'remove_node'
2020-04-12 23:24:12: ERROR[Main]: 	/usr/local/share/minetest/builtin/game/item.lua:621: in function </usr/local/share/minetest/builtin/game/item.lua:550>

So, one of my textline:lcd's was empty again not drawing text at all, seemingly lost its text entity.
Usually I've worked around this situation by digging it and placing again but this time digging it crashed whole server.

[S-S-X]

Also looking at sources it seems that issue has a lot to do with invalid text entity as it crashed while enumerating entities and text entity was somhow broken:
https://github.com/gbl08ma/textline/blob/636c776446c3fc831376335b72bb48281fb6ab11/init.lua#L46

It is also possible, but unlikely, that there was some other invalid entity and text entity was simply gone. Does not really matter, fix would be to verify that entity object can be actually used before attempting to use it.

[BuckarooBanzay]

Another one:

2020-07-22 07:03:25: ERROR[Server]: [monitoring] catched error: /data/world//worldmods/pipeworks/luaentity.lua:362: attempt to call method '_add_loaded' (a nil value)
2020-07-22 07:03:31: ERROR[Main]: ServerError: AsyncErr: ServerThread::run Lua: Runtime error from mod 'textline' in callback item_OnPlace(): Runtime error from mod 'textline' in callback node_on_destruct(): /data/world//worldmods/textline/init.lua:46: attempt to index a nil value
2020-07-22 07:03:31: ERROR[Main]: stack traceback:
2020-07-22 07:03:31: ERROR[Main]: 	/data/world//worldmods/textline/init.lua:46: in function 'clearscreen'
2020-07-22 07:03:31: ERROR[Main]: 	/data/world//worldmods/textline/init.lua:116: in function </data/world//worldmods/textline/init.lua:115>
2020-07-22 07:03:31: ERROR[Main]: 	[C]: in function 'add_node'
2020-07-22 07:03:31: ERROR[Main]: 	/data/world//worldmods/textline/init.lua:106: in function 'after_place_node'
2020-07-22 07:03:31: ERROR[Main]: 	/usr/local/share/minetest/builtin/game/item.lua:385: in function </usr/local/share/minetest/builtin/game/item.lua:258>
2020-07-22 07:03:31: ERROR[Main]: stack traceback:
2020-07-22 07:03:31: ERROR[Main]: 	[C]: in function 'add_node'
2020-07-22 07:03:31: ERROR[Main]: 	/data/world//worldmods/textline/init.lua:106: in function 'after_place_node'
2020-07-22 07:03:31: ERROR[Main]: 	/usr/local/share/minetest/builtin/game/item.lua:385: in function </usr/local/share/minetest/builtin/game/item.lua:258>