bugfix on 'NoneType' object has no attribute 'caption'

app.py

@@ -150,9 +150,13 @@ if ctx.video_processor:
 # Placeholder for showing captions
 placeholder = st.empty()
 if ctx.state.playing:
-    placeholder.markdown("**Caption:** _Waiting for inference…_")
+    placeholder.markdown("**Caption:** _Waiting for first inference…_")
     while ctx.state.playing:
-        txt = ctx.video_processor.caption or "_…thinking…_"
+        vp = ctx.video_processor
+        if vp is not None:
+            txt = vp.caption or "_…thinking…_"
+        else:
+            txt = "_…loading…_"
         placeholder.markdown(f"**Caption:** {txt}")
         time.sleep(0.1)
 else: