Filter empty `clear_text`

chall.py

@@ -357,6 +357,9 @@ class Chall(GeneratorBasedBuilder):
                 segment_data["raw_text"] = raw_text = self.get_raw_text(segment["words"])
                 segment_data["clear_text"] = self.get_clear_text(raw_text)
 
+                if not segment_data["clear_text"].strip():
+                    continue
+
                 start_time = segment["words"][0]["start"]
                 end_time = segment["words"][-1]["end"]
                 start_frame = int(_SAMPLE_RATE * start_time)