code: public static final FastBuildTree throwableToTree(String id, String nodeID, Throwable error) {
  		FastBuildTree msg = new FastBuildTree(7);
  
  		msg.putUnsafe("id", id);
  		msg.putUnsafe("ver", PROTOCOL_VERSION);
  		msg.putUnsafe("sender", nodeID);
  		msg.putUnsafe("success", false);
  		if (error != null) {
  
  			// Convert to Throwable to MoleculerError
  			MoleculerError moleculerError;
  			if (error instanceof CompletionException) {
  				error = error.getCause();
  			}
  			if (error instanceof MoleculerError) {
  				moleculerError = (MoleculerError) error;
  			} else {
  
  				// Unknown (DB? Heap?) issue, maybe its an retryable error
  				String message = String.valueOf(error.getMessage());
  				message = message.replace('\r', ' ').replace('\n', ' ').trim();
  				moleculerError = new MoleculerError(message, error, "MoleculerError", nodeID, false, 500,
  						"UNKNOWN_ERROR");
  			}
  
  			// Convert MoleculerError to JSON
  			FastBuildTree errorMap = new FastBuildTree(8);
  			msg.putUnsafe("error", errorMap);
  			moleculerError.toTree(errorMap);
  		}
  		return msg;
  	}
docs: --- CONVERT THROWABLE TO RESPONSE MESSAGE ---