fix: check if df in st.session_state keys()

pages/1_📈_Plotting.py

@@ -41,9 +41,10 @@ if 'df' in list(st.session_state.keys()):
 else:
     st.caption("Upload your data using the sidebar and select a plot-type to start :sunglasses:")
 
-df_base = st.dataframe(st.session_state.df)
+df_base = st.dataframe(st.session_state.df) if 'df' in list(st.session_state.keys()) else pd.DataFrame()
 n = len(df_base)
-st.info("Your data has {} samples.")
-n_plot = st.slider("How many samples do you want to plot in the same graph", list(range(n)))
-st.write(f"Action: {plot} using {n_plot} samples")
-st.button("Plot now! 📊")
+if n:
+    st.info("Your data has {} samples.")
+    n_plot = st.slider("How many samples do you want to plot in the same graph", list(range(n)))
+    st.write(f"Action: {plot} using {n_plot} samples")
+    st.button("Plot now! 📊")