minor fixes

cmd/client/client.go

@@ -274,6 +274,9 @@ func getResults(c *Client) ([][]float64, error) {
 		if !data.Success {
 			return nil, fmt.Errorf("api response error: %v", data.Error)
 		}
+		if len(data.Result[sensorID]) == 0 {
+			return nil, fmt.Errorf("no results returned - is your sensorID '%s' correct?", sensorID)
+		}
 		changeSlice := make([]float64, hoursInADay)
 		for j := range changeSlice {
 			changeSlice[j] = data.Result[sensorID][j].Change

cmd/root.go

@@ -112,7 +112,7 @@ func initConfig() {
 func promtUserConfig() error {
 	urlPrompt := prompter.Prompt("Home Assistant URL - e.g. http://localhost:8123", "")
 	token := prompter.Password("Home Assistant Long-Lived Access Token")
-	sensor := prompter.Prompt("Power sensor entity ID - e.g. sensor.power", "")
+	sensorID := prompter.Prompt("Power sensor entity ID - e.g. sensor.power", "")
 
 	haURL, err := url.Parse(urlPrompt)
 	if haURL.Scheme == "" {
@@ -124,6 +124,6 @@ func promtUserConfig() error {
 
 	viper.Set("api_key", token)
 	viper.Set("url", haURL.String())
-	viper.Set("sensor", sensor)
+	viper.Set("sensor_id", sensorID)
 	return nil
 }