IO access error when using the file system tracer

[tusmester]

When using the file system tracer in an asp.net core web application, this exception is thrown:

The process cannot access the file '...\App_Data\DetailedLog\detailedlog_20200114-141132Z.log' because it is being used by another process.

  at System.IO.FileStream.ValidateFileHandle(SafeFileHandle fileHandle)
   at System.IO.FileStream.CreateFileOpenHandle(FileMode mode, FileShare share, FileOptions options)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)
   at System.IO.StreamWriter.ValidateArgsAndOpenPath(String path, Boolean append, Encoding encoding, Int32 bufferSize)
   at System.IO.StreamWriter..ctor(String path, Boolean append)
   at SenseNet.Diagnostics.SnFileSystemTracer.WriteBatch(String text) in D:\Dev\github\sn-tools\src\SenseNet.Tools\Diagnostics\SnFileSystemTracer.cs:line 64

To use the tracer, add this line to the repo building code:

var repositoryBuilder = new RepositoryBuilder()    
    .UseTracer(new SnFileSystemTracer())