The shortcut key "q" and "ctrl+z" is invalid

[Bryan2Chow]

Hi, Thanks for your nice work!
Following the annotation on the README. First, I tagged an entity "机器", pressed shortcut key 'q'. The entity was deleted. Then, I pressed "ctrl + z", the full text of the imported file disappear and I got an error as follows, and have no idea to deal with it.

Could you please tell me what part of the process went wrong? and how to fix it?
I am very pleased to hear from you on the question's comments.

[FXLP]

Hi, Thanks for your nice work!
Following the annotation on the README. First, I tagged an entity "机器", pressed shortcut key 'q'. The entity was deleted. Then, I pressed "ctrl + z", the full text of the imported file disappear and I got an error as follows, and have no idea to deal with it.

Could you please tell me what part of the process went wrong? and how to fix it?
I am very pleased to hear from you on the question's comments.

I also encountered this problem, have you solved it?