Memory exhaustion problem fixed

print_r() on an exception dumps its full stack trace including every function argument at every frame (PHP includes args in traces by default). When a failure happens deep in a call chain carrying large data (e.g. IAAS repository sync processing big file listings/models), this re-serializes that data once per frame and can exhaust the PHP memory limit just while logging the error. Switch to getMessage() + getTraceAsString(), matching the existing pattern in setFinishedWithError().