update text style on line 127 function _convertTextStyle

[Tadix]

  TextStyle _convertTextStyle(
      bool isHidden, BuildContext context, common.TextStyleSpec? textStyle) {
    Color? color = textStyle?.color != null
        ? ColorUtil.toDartColor(textStyle!.color!)
        : null;
    if (isHidden) {
      // Use a default color for hidden legend entries if none is provided.
      color ??=  Theme.of(context).textTheme.bodyLarge!.color; // here replace "body1" by bodyLarge on somme new parameters
      color = color!.withOpacity(0.26);
    }

    return new TextStyle(
        inherit: true,
        fontFamily: textStyle?.fontFamily,
        fontSize: textStyle?.fontSize != null
            ? textStyle!.fontSize!.toDouble()
            : null,
        color: color);
   }