fix/flac: Actually print relevant incorrect type (#49)

* fix/flac: Actually print relevant incorrect type

`si` will always be `(*meta.StreamInfo)`, the relevant type is
`block.Header.Type` which implements `Stringer`

* Update flac.go

Co-authored-by: Robin <mewmew@users.noreply.github.com>

Co-authored-by: Robin <mewmew@users.noreply.github.com>

flac.go

@@ -184,7 +184,7 @@ func (stream *Stream) parseStreamInfo() (block *meta.Block, err error) {
 	}
 	si, ok := block.Body.(*meta.StreamInfo)
 	if !ok {
-		return block, fmt.Errorf("flac.parseStreamInfo: incorrect type of first metadata block; expected *meta.StreamInfo, got %T", si)
+		return block, fmt.Errorf("flac.parseStreamInfo: incorrect type of first metadata block; expected *meta.StreamInfo, got %T", block.Body)
 	}
 	stream.Info = si
 	return block, nil