You got the answers in this thread, why not check it?
i get this error when trying to open pointshop 2 on a server i played before.
[ERROR] lua/includes/extensions/net.lua:182: net.ReadType: Couldn't read type 31
1. error - [C]:-1
2. ReadType - lua/includes/extensions/net.lua:182
3. ReadType - lua/includes/extensions/net.lua:121
4. ReadType - lua/includes/extensions/net.lua:124
5. ReadType - lua/includes/extensions/net.lua:124
6. ReadType - lua/includes/extensions/net.lua:124
7. ReadTable - lua/includes/extensions/net.lua:124
8. func - addons/libk/lua/libk/client/cl_libk_baseview.lua:65
9. unknown - lua/includes/extensions/net.lua:32
GLib.Loader : Running pack file "GLib", deserialization took 174.21 ms (229 total files, 807.08 KiB).
GLib.Loader : Running pack file "GLibAddons", deserialization took 13.06 µs (0 total files, 16.00 B).
I didnt have this issue until i got banned and then came back. I tried a fresh install of gmod still no luck.
You got the answers in this thread, why not check it?