Trying to encode content without audio gives "Unhandled exception. System.Exception: No audio stream found"

[toasterberry]

Trying to encode any content without an audio track, whether a video or a GIF file, throws this error:

Unhandled exception. System.Exception: No audio stream found
at FastVideoDSEncoder.FFMpegDecoder..ctor(String srcPath, Int64 startPts, Int32 videoStreamId, Int32 audioStreamId)
at FastVideoDSEncoder.FvEncoder.Encode(String inFile, String outFile, Int32 jobCount)
at FastVideoDS.Program.<>c.b__1_1(Options opt)
at CommandLine.ParserResultExtensions.WithParsed[T](ParserResult1 result, Action1 action)
at FastVideoDS.Program.FFMpegTest(String[] args)
at FastVideoDS.Program.Main(String[] args)