adding backtracking prediction to the app

app.py

@@ -1,5 +1,5 @@
 import streamlit as st
-from sudoku.train import SudokuTrialErrorLightning
+from sudoku.train import SudokuTrialErrorLightning, TrialEveryPosException
 from sudoku.helper import display_as_dataframe, get_grid_number_soluce
 import numpy as np
 import re
@@ -116,7 +116,14 @@ if n_sol==1:
     while new_X.sum()<729:
         i+=1
         st.markdown(f'iteration {i}')
-        new_X = model.predict(new_X)
+        try:
+            new_X = model.predict(new_X)
+        except TrialEveryPosException:
+            st.markdown('''## The grid is super evil!
+            please share it as A Discussion in the `Community` tab.
+            Except if it is this one: https://www.telegraph.co.uk/news/science/science-news/9359579/Worlds-hardest-sudoku-can-you-crack-it.html''')
+            is_valid, new_X = model.backtracking_predict(new_X)
+            assert is_valid
         st.html(display_as_dataframe(new_X).to_html(escape=False, index=False))
         new_X_sum = new_X.sum()
         assert new_X_sum> X_sum