Enhance pagination logic and session state management in app.py

- Improved navigation controls by ensuring the current page is correctly initialized and updated, preventing potential errors when accessing pagination.
- Added checks to maintain session state integrity, ensuring that 'current_page' is set appropriately and relevant session data is cleared upon navigation.
- Enhanced user experience by providing clearer feedback on the current page being displayed.

app.py

@@ -197,16 +197,21 @@ with tab2:
         pagination_cols = st.columns([4, 1, 1, 1, 4])
         with pagination_cols[1]:
             if st.button("← Previous", disabled=st.session_state.current_page == 0):
-                st.session_state.current_page -= 1
-                if 'player_frame' in st.session_state:
-                    del st.session_state['player_frame']
-                    del st.session_state['stack_frame']
+                if st.session_state['current_page'] > 0:
+                    st.session_state.current_page -= 1
+                    if 'player_frame' in st.session_state:
+                        del st.session_state['player_frame']
+                        del st.session_state['stack_frame']
 
         with pagination_cols[2]:
             st.markdown(f"**Page {st.session_state.current_page + 1} of {total_pages}**", unsafe_allow_html=True)
+            
         with pagination_cols[3]:
             if st.button("Next →", disabled=st.session_state.current_page == total_pages - 1):
-                st.session_state.current_page += 1
+                if 'current_page' not in st.session_state:
+                    st.session_state.current_page = 1
+                else:
+                    st.session_state.current_page += 1
                 if 'player_frame' in st.session_state:
                     del st.session_state['player_frame']
                     del st.session_state['stack_frame']