[sociald] Improve debugging in error case. Contributes to JB#16288
[sociald] Improve debugging in error case. Contributes to JB#16288

This commit adds extra debugging so that if errors occur in the
future, we can easily get more information about which error
occurred.

Contributes to JB#16288

rainisto/buteo-sync-plugins-social,rainisto/buteo-sync-plugins-social