Implement base MissingValues strategies

frontend/pages/visualization.py

@@ -5,8 +5,8 @@ import seaborn as sns
 st.header("Data Visualization")
 
 
-if "data" in st.session_state:
-    data = st.session_state.data
+if "working_data" in st.session_state:
+    data = st.session_state.working_data
 
     st.subheader("Histogram")
     column_to_plot = st.selectbox("Select Column for Histogram", data.columns)