Errors for building kernelstub

[max-pod]

Distribution (run cat /etc/os-release):
NAME="Pop!_OS"
VERSION="21.10"
ID=pop
ID_LIKE="ubuntu debian"
PRETTY_NAME="Pop!_OS 21.10"
VERSION_ID="21.10"
HOME_URL="https://pop.system76.com"
SUPPORT_URL="https://support.system76.com"
BUG_REPORT_URL="https://github.com/pop-os/pop/issues"
PRIVACY_POLICY_URL="https://system76.com/privacy"
VERSION_CODENAME=impish
UBUNTU_CODENAME=impish
LOGO=distributor-logo-pop-os

Related Application and/or Package Version (run apt policy $PACKAGE NAME):
kernelstub:
Installed: 3.1.4163191158421.10de5b292
Candidate: 3.1.4163191158421.10de5b292
Version table:
*** 3.1.4163191158421.10~de5b292 1001
1001 http://apt.pop-os.org/release impish/main amd64 Packages
1001 http://apt.pop-os.org/release impish/main i386 Packages
100 /var/lib/dpkg/status

± % apt policy python                                                     !2332
python:
  Installed: (none)
  Candidate: 2.7.17-2pop1~1580508288~21.10~6895a24
  Version table:
     2.7.17-2pop1~1580508288~21.10~6895a24 1001
       1001 http://apt.pop-os.org/release impish/main amd64 Packages
       1001 http://apt.pop-os.org/release impish/main i386 Packages

maxpod@pop-os ~/kernelstub [master]
± % apt policy python3                                                    !2333
python3:
  Installed: 3.9.4-1build1
  Candidate: 3.9.4-1build1
  Version table:
 *** 3.9.4-1build1 500
        500 http://us.archive.ubuntu.com/ubuntu impish/main amd64 Packages
        100 /var/lib/dpkg/status

Issue/Bug Description:
Error for trying to install dependencies and error for trying to build & install kernelstub.

1. install build dependencies, git clone, and try to build kernelstub -> error
2. sudo apt remove kernelstub / build & install kernelstub -> error

Steps to reproduce (if you know):

Expected behavior:
Perhaps not so many errors.

Error for installing self-built kernelstub:

± % sudo dpkg -i ../kernelstub*.deb                                       !2324
(Reading database ... 334988 files and directories currently installed.)
Preparing to unpack ../kernelstub_3.1.4_all.deb ...
Unpacking kernelstub (3.1.4) over (3.1.4~1631911584~21.10~de5b292) ...
Setting up kernelstub (3.1.4) ...
kernelstub.Config    : INFO     Looking for configuration...
Traceback (most recent call last):
  File "/usr/bin/kernelstub", line 244, in <module>
    main()
  File "/usr/bin/kernelstub", line 241, in main
    kernelstub.main(args)
  File "/usr/lib/python3/dist-packages/kernelstub/application.py", line 142, in main
    config = Config.Config()
  File "/usr/lib/python3/dist-packages/kernelstub/config.py", line 50, in __init__
    self.config = self.load_config()
  File "/usr/lib/python3/dist-packages/kernelstub/config.py", line 60, in load_config
    self.config = json.load(config_file)
  File "/usr/lib/python3.9/json/__init__.py", line 293, in load
    return loads(fp.read(),
  File "/usr/lib/python3.9/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.9/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.9/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 22 column 5 (char 450)
dpkg: error processing package kernelstub (--install):
 installed kernelstub package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 kernelstub

sudo apt-build-dep kernelstub

± % sudo apt build-dep kernelstub                                         !2329
Reading package lists... Done
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up kernelstub (3.1.4~1631911584~21.10~de5b292) ...
kernelstub.Config    : INFO     Looking for configuration...
Traceback (most recent call last):
  File "/usr/bin/kernelstub", line 244, in <module>
    main()
  File "/usr/bin/kernelstub", line 241, in main
    kernelstub.main(args)
  File "/usr/lib/python3/dist-packages/kernelstub/application.py", line 142, in 
main
    config = Config.Config()
  File "/usr/lib/python3/dist-packages/kernelstub/config.py", line 50, in __init
__
    self.config = self.load_config()
  File "/usr/lib/python3/dist-packages/kernelstub/config.py", line 60, in load_c
onfig
    self.config = json.load(config_file)
  File "/usr/lib/python3.9/json/__init__.py", line 293, in load
    return loads(fp.read(),
  File "/usr/lib/python3.9/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.9/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.9/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 22 column 5 (char 450)
dpkg: error processing package kernelstub (--configure):
 installed kernelstub package post-installation script subprocess returned error
 exit status 1
Errors were encountered while processing:
 kernelstub
E: Sub-process /usr/bin/dpkg returned an error code (1)
E: Failed to process build dependencies

[logilype]

Is it solved now? I have a similar issue, but if I run sudo kernelstub