Fix broken contrib discussion search

[iMattPro]

Fixes #416

This is not possible for me test in any capacity locally. So I had to really on help from Claude on this one.

Summary of Fixes

1. get_document_url() method (lines 526-575) - Defense in depth

• Added validation to ensure $params is a valid non-empty array
• Added explicit checks for all required parameters based on route type
• Returns empty string if any required parameter is missing
• This prevents the routing errors at the template level

2. get_posts() method (lines 667-704) - Fixes support topic error

• Added validation to check if unserialized $url_params is a valid non-empty array
• Only adds documents to results if URL parameters are valid
• The existing post_url field already contains contrib_type and contrib from the database
• Prevents invalid posts from being added to search results

3. get_contribs() method (lines 714-748) - Prevents contrib route errors

• Added validation to check if contrib_type_obj exists before accessing its properties
• Only adds documents if contrib type is valid
• Prevents invalid contribs from being added to search results

4. get_faqs() method (lines 758-794) - Fixes FAQ item error

• Added validation to check if contrib_type_obj exists before accessing its properties
• Only adds documents if contrib type is valid
• Prevents invalid FAQs from being added to search results

These fixes work in layers:

• First layer: The get_*() methods filter out any documents with invalid or missing parameters
• Second layer: The get_document_url() method validates all required parameters are present before attempting to generate a route