filter removes duplicates

app/config.go

@@ -110,11 +110,11 @@ func ParseConfig(configPath string) (*Config, error) {
 }
 
 func (fu *FeedURL) UnmarshalYAML(node *yaml.Node) error {
-	*fu = []string{""}
 	switch node.Kind {
 	case yaml.SequenceNode:
 		return node.Decode((*[]string)(fu))
 	case yaml.ScalarNode:
+		*fu = []string{""}
 		return node.Decode(&(*fu)[0])
 	}
 	return fmt.Errorf("unexpected node type: %s, at %d:%d", node.ShortTag(), node.Line, node.Column)

app/db.go

@@ -78,6 +78,7 @@ func (d *db) Filter(entries []parser.FeedEntry) ([]parser.FeedEntry, error) {
 	for _, entry := range entries {
 		if _, ok := d.seenLinks[entry.Link]; !ok {
 			filteredEntries = append(filteredEntries, entry)
+			d.seenLinks[entry.Link] = struct{}{}
 		}
 	}
 	return filteredEntries, nil