Close #3474301 Add better error handling for ConfigSnapshotServiceProvider.
Turns errors like
[warning] Trying to access array offset on false ConfigSnapshotServiceProvider.php:30
[warning] Trying to access array offset on false ConfigSnapshotServiceProvider.php:30
[warning] Trying to access array offset on false ConfigSnapshotServiceProvider.php:30
[warning] Trying to access array offset on false ConfigSnapshotServiceProvider.php:31
[warning] Trying to access array offset on false ConfigSnapshotServiceProvider.php:32
[warning] Trying to access array offset on false ConfigSnapshotServiceProvider.php:33
Into errors like
Error processing config ID config_snapshot.snapshot.config_sync.module.module_name: Invalid snapshot data for config ID config_snapshot.snapshot.config_sync.module.module_name