Unhandled 404 from Graph API (special character in folder path) causes full indexing failure

During SharePoint ingestion for the Azure AI Search → Copilot Studio push connector, the indexing pipeline fails entirely when encountering a folder path with special characters (specifically #).
The Graph API request returns a 404 Not Found, which is not handled within the file enumeration logic. This exception propagates up and terminates the entire run.

Root Cause

Folder path contains a special character (#) → e.g. Submission #1
Path-based Graph API call fails (404)
Exception is not caught inside list_files() / list_all_files()
Error bubbles up to _dispatch_files() and crashes execution

Impact
A single folder failure results in a complete pipeline breakdown:

list_all_files() never returns
File enumeration is incomplete
Queue (sp-indexer-q) receives zero messages
sp_worker is never triggered
Zero documents are indexed

This can occur after several minutes of crawling, making the failure non-obvious.

Steps to Reproduce

Create a SharePoint folder with # in the name (e.g. Submission #1)
Run the indexer with path-based traversal
Observe 404 response from Graph API
Pipeline terminates with no documents indexed

Expected Behavior

Connector should handle special characters in paths (proper encoding or alternative approach)
Failures on individual folders should be gracefully handled and skipped
Remaining files should continue to be indexed