Bugfix: the language must be string (and not an array)

patacrep/content/song.py

@@ -92,7 +92,7 @@ def parse(keyword, argument, contentlist, config):
                         config,
                         ))
                     songlist.append(renderer)
-                    config["_languages"].update(renderer.song.language)
+                    config["_languages"].add(renderer.song.language)
             if len(songlist) > before:
                 break
         if len(songlist) == before:

patacrep/latex/ast.py

@@ -46,7 +46,7 @@ class Command(AST):
         self.optional = optional
 
         if name == r'\selectlanguage':
-            self.metadata['@language'] = self.mandatory
+            self.metadata['@language'] = self.mandatory[0]
 
     def __str__(self):
         if self.name in [r'\emph']: