There's an error that forces me to exit the game if I open my Todo list now.

Hmm. Thanks for the report.
I'm currently in the process of moving flats and don't have a working computer.

Can you please post the error here? Then I can try to tell you how to fix it or do a patch from my phone.

Yes here you go:

The mod Todo List (18.0.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Todo-List::on_gui_click (ID 1)
Unknown sprite "utility/remove"
stack traceback:
Todo-List/todo/ui/main_frame.lua:429: in function 'add_row_to_main_table'
Todo-List/todo/ui/main_frame.lua:399: in function 'add_subtask_to_main_table'
Todo-List/todo/ui/main_frame.lua:312: in function 'add_subtasks_to_task_table'
Todo-List/todo/ui/main_frame.lua:295: in function 'add_task_to_table'
Todo-List/todo/features/main_ui.lua:71: in function 'refresh_task_table'
Todo-List/todo/features/main_ui.lua:32: in function 'on_maximize_button_click'
Todo-List/todo/todo.lua:71: in function 'on_gui_click'
Todo-List/control.lua:20: in function <Todo-List/control.lua:19>
stack traceback:
[C]: in function 'add'
Todo-List/todo/ui/main_frame.lua:429: in function 'add_row_to_main_table'
Todo-List/todo/ui/main_frame.lua:399: in function 'add_subtask_to_main_table'
Todo-List/todo/ui/main_frame.lua:312: in function 'add_subtasks_to_task_table'
Todo-List/todo/ui/main_frame.lua:295: in function 'add_task_to_table'
Todo-List/todo/features/main_ui.lua:71: in function 'refresh_task_table'
Todo-List/todo/features/main_ui.lua:32: in function 'on_maximize_button_click'
Todo-List/todo/todo.lua:71: in function 'on_gui_click'
Todo-List/control.lua:20: in function <Todo-List/control.lua:19>

Thanks. Apparently they changed the sprite names.. I'll have to investigate that. I try to patch it ASAP, but unfortunately it will be a couple days :(

I just got this error but when I tried to add a subtask. So my guess is that it's exactly at the part of creating the subtrask row that is failing. My guess is that iborpastan already has a todo list with subtasks which is why they aren't able to open their list anymore. I am able to open my list but I don't have any subtasks yet.

Yes. The problem is that the icon for the delete button of a subtask does not exist anymore. At least not under that name.

The fix should be easy. Change the name of the icon to the new one.

It is indeed the case that I have subtasks.

I don't remember what old icon was, but here is quick fix.
In main_frame.lua row 395, change so it will look like this:
sprite = "utility/trash",

Thanks! I changed the line and it works.

Please fix, this just crashed our server.

Yikes! Same thing just crashed our server as well. Please fix :)

Sorry for the delay. I am still moving flats and only now have the machine from my new workplace up and running.
A new version has been released that should fix the problem.

Thanks to Dilise for the pull request on Github.