Error with weird chars on history backend

[spothound]

When cat this file with the logger enabled this error is produced:

Traceback (most recent call last):
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xonsh/main.py", line 420, in main
    sys.exit(main_xonsh(args))
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xonsh/main.py", line 458, in main_xonsh
    shell.shell.cmdloop()
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xonsh/ptk_shell/shell.py", line 259, in cmdloop
    self.default(line)
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xonsh/base_shell.py", line 377, in default
    self._append_history(inp=src, ts=[ts0, ts1], tee_out=tee_out)
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xonsh/base_shell.py", line 412, in _append_history
    hist.append(info)
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xontrib/json_syslog_history_backend.py", line 63, in append
    self._register_cmd(cmd)
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xontrib/json_syslog_history_backend.py", line 85, in _register_cmd
    self.write_logs(log_line)
  File "/tmp/.mount_xonshkuQ9Sa/opt/python3.8/lib/python3.8/site-packages/xontrib/json_syslog_history_backend.py", line 94, in write_logs
    fd.write(' '.join(log_string.split())+"\n")
UnicodeEncodeError: 'utf-8' codec can't encode character '\udcf3' in position 129817: surrogates not allowed
Xonsh encountered an issue during launch
Failback to /bin/xonsh

We should check the cause and fix it ASAP.