web生成图片当模板绑定的数据值为null时出现空指针异常

[NaChoFan]

Describe the bug
使用webReport.Report.RegisterData向模板注入数据时，如果某个字段为null会引发空指针。
在BarcodeObject.cs中628行；string value = Report.Calc(expression).ToString();
Report.Calc(expression)=null导致ToString空指针
应修复
string value = (Report.Calc(expression) ?? string.Empty).ToString();

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[BogdanStg]

Hello!

Your approach is correct. To work around this issue, you can also enable the option report.ConvertNulls = true; this option automatically converts null to an empty string, 0 or false, depending on the type.