Opaque traceback on malformed pyproject.toml

[lordmauve]

A user experienced a crash due to a malformed pyproject.toml:

Traceback (most recent call last):
  File "/home/user/project/.venv/bin/thx", line 5, in <module>
    from thx.main import main
  File "/home/user/project/.venv/lib/python3.12/site-packages/thx/main.py", line 63, in <module>
    @click.group(cls=ThxGroup, chain=True, invoke_without_command=True, help=__doc__)
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/click/decorators.py", line 238, in decorator
    cmd = cls(
          ^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/thx/main.py", line 39, in __init__
    self.config = load_config()
                  ^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/thx/config.py", line 135, in load_config
    data = tomli.loads(content).get("tool", {}).get("thx", {})
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/tomli/_parser.py", line 107, in loads
    pos = key_value_rule(src, pos, out, header, parse_float)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/tomli/_parser.py", line 331, in key_value_rule
    pos, key, value = parse_key_value_pair(src, pos, parse_float)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/tomli/_parser.py", line 374, in parse_key_value_pair
    pos, value = parse_value(src, pos, parse_float)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/tomli/_parser.py", line 621, in parse_value
    return parse_array(src, pos, parse_float)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/tomli/_parser.py", line 425, in parse_array
    pos, val = parse_value(src, pos, parse_float)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/user/project/.venv/lib/python3.12/site-packages/tomli/_parser.py", line 654, in parse_value
    raise suffixed_err(src, pos, "Invalid value")
tomli.TOMLDecodeError: Invalid value (at line 13, column 5)

The user was not familiar with TOML and made a mistake in editing it. But this error did not guide them towards the root cause and they were unable to self-resolve it.