Summary of the issue

Can not open Export xlsx in ASP.NET Core 4.5.2 in browser using InMemoryReport I using .Net Standard (not .Net Core) in .Net Framework 4.6.1

Environment

backend: ASP.NET Core EPPlus, .Net Standard (not .Net Core) in .Net Framework 4.6.1 frontend: Chrome, angularjs

The in-use version:
Operating system: 
Win7, Visual studio 2017, 

## Example code/Steps to reproduce:
1. controller same with code example: 
HomeController.InMemoryReport()
{
            byte[] reportBytes;
            using (var package = createExcelPackage())
            {
                reportBytes = package.GetAsByteArray();
            }

            return File(reportBytes, XlsxContentType, "report.xlsx");
        }

2. Got web API response in front end to open excel in browser Chrome
response.data is the controller response.                
                    let blob = new Blob([response.data], {
                        type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
                    })
                    //To support IE 
                    if (navigator.appVersion.toString()
                        .indexOf('.NET') > 0)
                        window.navigator.msSaveBlob(blob, "report.xlsx");
                    //To support Chrome
                    else {
                        var a = document.createElement("a");
                        document.body.appendChild(a);
                        a.style = "display: none";
                        let url = window.URL.createObjectURL(blob);
                        a.href = url;
                        a.download = "report.xlsx";
                        a.click();
                        window.URL.revokeObjectURL(url);
                    }
                 });

## Output:
But it showed as:
"Excel cannot open the file... because the file format or file extension is not valid. Verify..corrupted and..."
I tried to change blob type to type: 'text/plain', but it does not work.

Exception message: Full Stack trace:

VahidN / EPPlus.Core

Does EPPLus ASP.NET Core support .Net Standard (not .Net Core) .Net framework 4.6.1 #46

Summary of the issue

Environment