fix(loadtest): panic when cut off brutally with ctrl+c (#139)

* fix: loadtest panic when cut off brutally with `ctrl+c`

* chore: nit

* chore: remove log msg

* chore: early return

cmd/loadtest/loadtest.go

@@ -318,8 +318,12 @@ func completeLoadTest(ctx context.Context, c *ethclient.Client, rpc *ethrpc.Clie
 	if err != nil {
 		log.Error().Err(err).Msg("There was an issue waiting for all transactions to be mined")
 	}
-	endTime := time.Now()
+	if len(loadTestResults) == 0 {
+		return errors.New("no transactions observed")
+	}
+
 	startTime := loadTestResults[0].RequestTime
+	endTime := time.Now()
 	log.Debug().Uint64("currentNonce", currentNonce).Uint64("final block number", finalBlockNumber).Msg("Got final block number")
 
 	if *inputLoadTestParams.ShouldProduceSummary {