Custom command causes `AttributeError: 'NoneType' object has no attribute 'has_text'`

[MayeulC]

Hello, I use the following snippet as part of my manuscript:

% Overleaf has an outdated inkscape version, try to work around it:
% Inspired from https://tex.stackexchange.com/a/650621
\def\overleafStripPrefix#1>{}
\def\isoverleaf{FF\fi
        \def\predicate{output}%
        \edef\predicate{\expandafter\overleafStripPrefix\meaning\predicate}%
        \edef\job{\jobname}%
        \ifx\job\predicate
}

Including just that in a tex file is enough to make flap abort.

Backtrace

$ flap main.tex flaped/
FLaP 0.6.0
Traceback (most recent call last):
  File "/home/mcantan/.local/bin/flap", line 8, in <module>
    sys.exit(main())
  File "/home/mcantan/.local/lib/python3.10/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/mcantan/.local/lib/python3.10/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/mcantan/.local/lib/python3.10/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/mcantan/.local/lib/python3.10/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/ui.py", line 117, in main
    .run(tex_file, output)
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/ui.py", line 43, in run
    request.execute()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/engine.py", line 84, in execute
    tokens = self._rewrite(self.read_root_tex,
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/engine.py", line 94, in _rewrite
    return parser.rewrite()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 90, in rewrite
    result += self._rewrite_one()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 98, in _rewrite_one
    return self._rewrite_command()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 114, in _rewrite_command
    return macro.rewrite(self)
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/macros/core.py", line 32, in rewrite
    self._execute(parser, invocation)
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/macros/core.py", line 43, in _execute
    self._rewritten_body = parser._spawn(body, dict()).rewrite()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 90, in rewrite
    result += self._rewrite_one()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 96, in _rewrite_one
    return self._rewrite_group()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 105, in _rewrite_group
    tokens += self._rewrite_one()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 96, in _rewrite_one
    return self._rewrite_group()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 105, in _rewrite_group
    tokens += self._rewrite_one()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 98, in _rewrite_one
    return self._rewrite_command()
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 114, in _rewrite_command
    return macro.rewrite(self)
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/macros/commons.py", line 112, in rewrite
    invocation = self._parse(parser)
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/macros/commons.py", line 64, in _parse
    self._capture_arguments(parser, invocation)
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/macros/commons.py", line 80, in _capture_arguments
    value = parser._evaluate_until(
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/parser.py", line 186, in _evaluate_until
    while not is_excluded(self._next_token):
  File "/home/mcantan/.local/lib/python3.10/site-packages/flap/latex/macros/commons.py", line 81, in <lambda>
    lambda token: token.has_text(next_token._text))
AttributeError: 'NoneType' object has no attribute 'has_text'

I tried to remove that snippet, but I'm encountering another issue. I'll isolate a reproducer and open a new issue.