`meson rewrite kwargs delete project / <option>` raises unhandled exception unless a dummy second value is passed

[igo95862]

Describe the bug
meson rewrite kwargs delete project / <option> raises unhandled exception unless a dummy second value is passed.

To Reproduce

Given following meson.build project() call:

project('bubblejail',
    version : '0.8.3',
    # Patch out these lines to install bubblejail's packages to site-packages
    default_options : {
        'python.purelibdir' : 'lib/bubblejail/python-packages',
        'python.platlibdir' : 'lib/bubblejail/python-packages',
    },
)

I tried to delete default_options (and version as a test) using meson rewrite:

meson rewrite kwargs delete project / default_options
meson rewrite kwargs delete project / version

This raises the following exception:

Traceback (most recent call last):
  File "/usr/lib/python3.12/site-packages/mesonbuild/rewriter.py", line 997, in list_to_dict
    result[i] = next(it)
                ^^^^^^^^
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.12/site-packages/mesonbuild/mesonmain.py", line 186, in run
    return options.run_func(options)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/mesonbuild/rewriter.py", line 1073, in run
    raise e
  File "/usr/lib/python3.12/site-packages/mesonbuild/rewriter.py", line 1059, in run
    commands = cli_type_map[options.type](options)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/mesonbuild/rewriter.py", line 1018, in generate_kwargs
    'kwargs': list_to_dict(options.kwargs),
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/mesonbuild/rewriter.py", line 999, in list_to_dict
    raise TypeError('in_list parameter of list_to_dict must have an even length.')
TypeError: in_list parameter of list_to_dict must have an even length.

ERROR: Unhandled python exception

    This is a Meson bug and should be reported!

I found a work-around with passing a second dummy value and it worked:

meson rewrite kwargs delete project / default_options ""

Expected behavior
meson rewrite removes the kwargs without dummy values.

system parameters

• Native build
• Arch Linux
• Python 3.12
• meson 1.4.0