Config value mermaid_sequence_config not parsed correctly

[fpreiss]

When trying to override the sequence diagram configuration with the mermaid_sequence_config
option, sphinx will give the following warning:

WARNING: The config value `mermaid_sequence_config' has type `str', defaults to `bool'.

At the time sphinx tries to write the output, it crashes with the following exception:

writing output... [ 87%] pages/examples
Exception occurred:
  File "VENVPATH/lib/python3.10/site-packages/sphinxcontrib/mermaid.py", line 182, in render_mm
    mm_args.extend("--configFile", self.builder.config.mermaid_sequence_config)
TypeError: list.extend() takes exactly one argument (2 given)

For my use case I found a workaround by passing the configFile parameter directly to the
parameter list mermaid_params:

mermaid_params = [
    "--configFile",
    "docs/_static/mermaid_config.json",
]

[jswongF5]

@fpreiss, What does your mermaid_config.json file look like? I don't see the same error message as you during the build when I use mermaid_sequence_config (I do see the same WARNING). I seem to unable to get it even loaded at all using the workaround (at least I doesn't seem like it is).

My mermaid config, docs/_static/mermaid_config.json:

{
    "theme": "dark"
}

And in my conf.py:

mermaid_params = [
    "--configFile",
    "docs/_static/mermaid_config.json",
]

If I do this in the actual mermaid diagram, it works.

.. mermaid::

   %%{init: {
      "theme": "dark"
   }}%%
   graph TD;
      A--->B