Fix: Audio Wave node uncreatable when ComfyUI/input has no audio (empty combo)

An empty combo ([],) can't be built by ComfyUI, so the node wouldn't add to the
canvas. _audio_files() now always returns at least a placeholder entry.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

nodes/audio_wave_segments.py

@@ -69,17 +69,23 @@ def _segments_from_boundaries(rms_n, times, duration, fps, starts, beats):
     return segs, bounds
 
 
+_NO_AUDIO = "(put an audio file in ComfyUI/input)"
+
+
 def _audio_files():
+    files = []
     try:
         import folder_paths
         d = folder_paths.get_input_directory()
         try:
-            return sorted(folder_paths.filter_files_content_types(os.listdir(d), ["audio", "video"]))
+            files = sorted(folder_paths.filter_files_content_types(os.listdir(d), ["audio", "video"]))
         except Exception:
             exts = (".wav", ".mp3", ".flac", ".ogg", ".m4a", ".aac")
-            return sorted(f for f in os.listdir(d) if f.lower().endswith(exts))
+            files = sorted(f for f in os.listdir(d) if f.lower().endswith(exts))
     except Exception:
-        return []
+        files = []
+    # A combo must never be empty, or ComfyUI can't build the node.
+    return files or [_NO_AUDIO]
 
 
 class AudioWaveSegments: