Improve Genius lyrics stability

Sometimes the first result in the Genius API response may not contain
the path to lyrics. In such cases, keep iterating on the next
result until the path is found.

spotdl/lyrics/providers/genius.py

@@ -79,7 +79,22 @@ class Genius(LyricBase):
         encoded_query = urllib.request.quote(query.replace(" ", "+"))
         search_url = self.base_search_url + encoded_query
         metadata = self._fetch_search_page(search_url)
-        lyric_url = metadata["response"]["sections"][0]["hits"][0]["result"]["path"]
+
+        lyric_url = None
+        for section in metadata["response"]["sections"]:
+            result = section["hits"][0]["result"]
+            try:
+                lyric_url = result["path"]
+                break
+            except KeyError:
+                pass
+
+        if lyric_url is None:
+            raise LyricsNotFoundError(
+                "Could not find any valid lyric paths in the "
+                "API response for the query {}".format(query)
+            )
+
         return self.base_url + lyric_url
 
     def from_query(self, query, linesep="\n", timeout=None):