Bug: "Cannot read properties of undefined (reading 'replace')" on search

[python3demon]

Environment

• Platform: Mobile Browser
• URL: dev.omarshafie.com/hadith/

Steps to Reproduce

1. Navigate to the Search Form page.
2. Select Sources: Bukhari, Muslim, Malik.
3. Input أنس بن مالك into the Sanad Pattern field.
4. Input إنما الأعمال بالنيات into the Hadith Query field.
5. Click the Submit button.

Expected Behavior

The search engine should parse the query, execute the visualization, and generate the Hadith Isnad tree.

Actual Behavior

The execution halts, displaying the following error message below the input fields:

Cannot read properties of undefined (reading 'replace')
Done in 6.427 seconds

(Note: I have attached a screenshot of the error state to this issue)