Changed the callback function name for the image uploader.

app.py

@@ -49,7 +49,10 @@ for i in st.session_state["chat_history"]:
 import numpy as np
 from PIL import Image
 
-img_file_buffer = st.file_uploader('Upload a PNG image', on_change= type=['png','jpg'])
+img_file_buffer = st.file_uploader('Upload a PNG image', on_change=uploader_callback type=['png','jpg'])
 if img_file_buffer is not None:
     image = Image.open(img_file_buffer)
-    img_array = np.array(image)
+    img_array = np.array(image)
+
+def uploader_callback():
+    print('Uploaded file')