TypeError: expected str, bytes or os.PathLike object, not NoneType

[Yutao-Jin]

macserver@MacServer ~ % /Users/macserver/Desktop/transmission-trackers.py

Traceback (most recent call last):
File "/Users/macserver/Desktop/transmission-trackers.py", line 54, in
cache_file = path.join(env.get('TEMP',env.get('TMP',None)) ,'.cache/trackers.txt')
File "/usr/local/Cellar/python@3.9/3.9.9/Frameworks/Python.framework/Versions/3.9/lib/python3.9/posixpath.py", line 76, in join
a = os.fspath(a)
TypeError: expected str, bytes or os.PathLike object, not NoneType

I'm using python 3.9.9 on macOS

[S-Riot]

This error comes up on Unix based systems. Basically, the script is searching for a temporary directory on the system environment settings and, when it doesn't find it, you get that error.
On Mac, specifically, go to the terminal and type:
env TMP
or
env TEMP
if those variables are not present you will receive the following message or similiar:
env: TMP: No such file or directory
In this case, you have to add a permanent enviromental variable. In order to do this, open a terminal window and type
nano .bash_profile
at the end of the file, add:
export TMP=/tmp
save and close the file, it's advisable to restart the computer.
This should solve the problem above.
In my case, just to let you know, I was working with UBUNTU 20.10 and after that, I had to tweak the permissons on the directory that is created by the python script inside the temporary directory.

[trotskylenin]

Same issue here.
I replaced None by '' and it worked.
The issue is not that TMP is not an environment variable in Unix systems, because that should be handled properly if the path is not found.
The issue is that None is not a valid value type for the second parameter of env.get

[trotskylenin]

Go to Case 6 in this url and you will see proper usage:
https://www.geeksforgeeks.org/python-os-environ-object/?ref=gcse

[trotskylenin]

I've just proposed a pull request to fix this.