[BUGFIX] Improve error handling for invalid guides.xml configuration

[CybotTM]

Summary

Instead of crashing with a PHP Fatal error when guides.xml contains invalid configuration, the guides entrypoint now catches InvalidTypeException and InvalidConfigurationException and displays a helpful error message.

Before:

PHP Fatal error:  Uncaught Symfony\Component\Config\Definition\Exception\InvalidTypeException: 
Invalid type for path "guides.theme". Expected "scalar", but got "array". in ...
Stack trace:
#0 ...
(20+ lines of stack trace)

After:

 Invalid guides.xml configuration 

Your guides.xml file contains a configuration error:
  Invalid type for path "guides.theme". Expected "scalar", but got "array".

Common causes:
  - Invalid or unknown XML element
  - Missing required attributes
  - Invalid attribute values or types

Run vendor/bin/typo3-guides lint-guides-xml for detailed validation.
See: https://docs.typo3.org/m/typo3/docs-how-to-document/main/en-us/GeneralConventions/GuideXml.html

Approach

This is a minimal fix that catches exceptions and provides a user-friendly error message. It's simple (~25 lines) but doesn't provide line numbers or specific validation details.

Alternative

See also the companion PR with a comprehensive fix that validates against XSD schema before loading, providing exact line/column numbers: #1118

Test plan

• Create a malformed guides.xml with <theme name="typo3docs" /> as child element
• Run bin/guides run --config=Documentation Documentation
• Verify helpful error message is shown instead of PHP Fatal error
• Verify valid guides.xml files still render correctly

[linawolf]

failing tests are unrelated, I need to fix them first

[garvinhicking]

I think this looks helpful... not too sure about possible impacts when catching these very specific exceptions, so I'd like some more vote/feedback on this patch, especially due to the AI usage.

[CybotTM]

@garvinhicking,

not too sure about possible impacts when catching these very specific exceptions, so I'd like some more vote/feedback on this patch

That's why I also provided a more comprehensive patch with #1118