fix CandlestickSeries constructor (#8664)

- likely a copy-pasta error from Series, where index=0 is passed to
  BaseSeries constructor, only now it was passed as SeriesType, which
  is subsequently set in CandlestickSeries constructor

Author: laur89

Common/CandlestickSeries.cs

@@ -72,9 +72,8 @@ public CandlestickSeries(string name, int index, string unit)
         /// <param name="name">Name of the chart series</param>
         /// <param name="unit">Unit of the series</param>
         public CandlestickSeries(string name, string unit)
-            : base(name, 0, unit)
+            : base(name, SeriesType.Candle, unit)
         {
-            SeriesType = SeriesType.Candle;
         }
 
         /// <summary>

Common/SeriesSampler.cs

@@ -239,7 +239,7 @@ private CandlestickSeries SampleCandlestickSeries(CandlestickSeries series, Date
             var startIndex = candlesticks.FindIndex(x => x.Time > nextSampleTime) - 1;
             if (startIndex < 0)
             {
-                // there's not value before the start, just return identity
+                // there's no value before the start, just return identity
                 return GetIdentitySeries(sampledSeries, series, start, stop, truncateValues);
             }
             if (candlesticks[startIndex].Time == nextSampleTime && nextSampleTime <= stop)

Common/Util/SeriesJsonConverter.cs

@@ -99,7 +99,7 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
 
                 default:
                     writer.WritePropertyName("values");
-                    serializer.Serialize(writer, (value as BaseSeries).Values);
+                    serializer.Serialize(writer, baseSeries.Values);
                     break;
             }