KeyError on unexpected/invalid tag

[riklaunim]

I'm using GrapesJS editor on the frontend in their MJML mode for customers to edit their templates and some time they still manage to somehow copy-paste a HTML tag like p which then causes mjml-python to throw a KeyError instead of pushing error to validation:

             ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/mjml2html.py", line 243, in mjml_to_html
    content = processing(mjBody, bodyHelpers, applyAttributes)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/mjml2html.py", line 123, in processing
    return component.render()
           ^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_body.py", line 54, in render
    children_str = self.renderChildren()
                   ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/_base.py", line 169, in renderChildren
    output += renderer(component)
              ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/_base.py", line 111, in <lambda>
    renderer = lambda component: component.render()
                                 ^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_section.py", line 149, in render
    return self.renderSimple()
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_section.py", line 181, in renderSimple
    section = self.renderSection()
              ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_section.py", line 258, in renderSection
    {self.renderWrappedChildren()}
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_section.py", line 298, in renderWrappedChildren
    {self.renderChildren(children, renderer=render_child)}
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/_base.py", line 169, in renderChildren
    output += renderer(component)
              ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_section.py", line 288, in render_child
    {component.render()}
     ^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_column.py", line 137, in render
    column_str = self.renderColumn() if (not self.hasGutter()) else self.renderGutter()
                 ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/mj_column.py", line 254, in renderColumn
    {self.renderChildren(children, renderer=render_child)}
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/elements/_base.py", line 164, in renderChildren
    component = initComponent(
                ^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mjml/core/api.py", line 17, in initComponent
    component_cls = components[name]
                    ~~~~~~~~~~^^^^^^
KeyError: 'p'

For something like this:

  <mj-body>
    <mj-section>
      <mj-column>
        <mj-text>Hello World</mj-text>
        <p>bug</p>
      </mj-column>
    </mj-section>
  </mj-body>
</mjml>

I've changed components[name] to components.get(name) and it seems to work ok-ish as it removes the invalid tag with its contents (it's good to recover other changes but no info about the invalid tag that got removed).

[FelixSchwarz]

Thank you for the report. Indeed, the code currently does not make any attempt in catching invalid markup. I'll put this on my todo list, maybe I can add some basic validation infrastructure.

However I don't want to just ignore errors silently. If you need something short term, you could try to preprocess the mjml for invalid tags (maybe everything except <mjml> and <mj-...>?).

[riklaunim]

Yes, silencing the error would not be the best.