[feature][bug] fix import packge error

CHANGELOG.md

@@ -57,6 +57,7 @@
 
 ## master
 
+* (2022.07.29) 修复在某些`Unity`版本导入后图表创建异常的问题
 * (2022.07.29) 增加`Axis`为`Time`时间轴时，支持次刻度和次分割线
 * (2022.07.28) 优化`Radar`雷达图效果
 * (2022.07.28) 增加`Serie`的`colorBy`参数配置取色策略

Runtime/Internal/XCThemeMgr.cs

@@ -56,10 +56,17 @@ namespace XCharts.Runtime
         {
             if (!XChartsMgr.themes.ContainsKey(themeName))
             {
+                ReloadThemeList();
+                if (XChartsMgr.themes.ContainsKey(themeName))
+                    return XChartsMgr.themes[themeName];
+                else
                     return null;
             }
+            else
+            {
                 return XChartsMgr.themes[themeName];
             }
+        }
 
         public static Theme LoadTheme(ThemeType type)
         {

Runtime/Serie/SerieHelper.cs

@@ -282,7 +282,7 @@ namespace XCharts.Runtime
         public static void GetItemColor(out Color32 color, out Color32 toColor,
             Serie serie, SerieData serieData, ThemeStyle theme, SerieState state = SerieState.Auto)
         {
-            var colorIndex = serie.colorByData? serieData.index : serie.context.colorIndex;
+            var colorIndex = serieData != null && serie.colorByData? serieData.index : serie.context.colorIndex;
             GetItemColor(out color, out toColor, serie, serieData, theme, colorIndex, state, true);
         }