Fix nil pointer dereference

restream/app/progress.go

@@ -68,7 +68,13 @@ func (p *ProgressIO) UnmarshalParser(pp *parse.ProgressIO) {
 	p.Sampling = pp.Sampling
 	p.Layout = pp.Layout
 	p.Channels = pp.Channels
-	p.AVstream.UnmarshalParser(pp.AVstream)
+
+	if pp.AVstream != nil {
+		p.AVstream = &AVstream{}
+		p.AVstream.UnmarshalParser(pp.AVstream)
+	} else {
+		p.AVstream = nil
+	}
 }
 
 func (p *ProgressIO) MarshalParser() parse.ProgressIO {

restream/app/progress_test.go

@@ -0,0 +1,49 @@
+package app
+
+import (
+	"testing"
+
+	"github.com/datarhei/core/v16/ffmpeg/parse"
+	"github.com/stretchr/testify/require"
+)
+
+func TestProgressIO(t *testing.T) {
+	original := parse.ProgressIO{
+		Address:  "",
+		Index:    0,
+		Stream:   0,
+		Format:   "",
+		Type:     "",
+		Codec:    "",
+		Coder:    "",
+		Frame:    0,
+		Keyframe: 0,
+		Framerate: struct {
+			Min     float64
+			Max     float64
+			Average float64
+		}{},
+		FPS:       0,
+		Packet:    0,
+		PPS:       0,
+		Size:      0,
+		Bitrate:   0,
+		Extradata: 0,
+		Pixfmt:    "",
+		Quantizer: 0,
+		Width:     0,
+		Height:    0,
+		Sampling:  0,
+		Layout:    "",
+		Channels:  0,
+		AVstream:  &parse.AVstream{},
+	}
+
+	p := ProgressIO{
+		AVstream: nil,
+	}
+	p.UnmarshalParser(&original)
+	restored := p.MarshalParser()
+
+	require.Equal(t, original, restored)
+}