Prettify error, fix tags and similar artists if empty

internal/app/modlastfm/command/artist.go

@@ -12,6 +12,10 @@ func (f *Fn) ArtistInfo(artist string, nickname string) string {
 	artistInfo, err := f.getArtistInfo(artist)
 
 	if err != nil {
+		if strings.HasPrefix(err.Error(), "LastfmError[6]") {
+			return "The artist you supplied could not be found"
+		}
+
 		return fmtError(err)
 	}
 
@@ -25,7 +29,7 @@ func (f *Fn) GetArtistTags(artist string, nickname string) string {
 
 	res, err := f.getArtistInfo(artist)
 
-	if err == nil {
+	if err == nil && len(res.Tags) > 0 {
 		tags = fmtArtistTags(res)
 	}
 
@@ -87,5 +91,9 @@ func fmtArtistSimilar(artist lastfm.ArtistGetInfo) string {
 		s = append(s, artist.Similars[i].Name)
 	}
 
-	return strings.Join(s, ", ")
+	if len(s) > 0 {
+		return strings.Join(s, ", ")
+	}
+
+	return "none"
 }