fix: improve error logging in FFI HTTP middleware to capture full error chain

[markphelps]

Summary

Enhanced error logging in the FFI HTTP middleware to capture the complete error chain instead of just the immediate source.

Changes

• Iterates through the entire error chain using source() recursively
• Uses Debug format for error sources to capture more detailed information
• Formats output to show the main error followed by the complete chain of causes

This makes debugging HTTP errors easier by providing full context of nested error scenarios.