put day for ProgrammeDayFragment in a ViewModel - should fix crash

app/src/main/java/fr/forum_thalie/tsumugi/ui/programme/ProgrammeDayFragment.kt

 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Observer
+import androidx.lifecycle.ViewModelProviders
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import fr.forum_thalie.tsumugi.R
     private lateinit var viewAdapter: RecyclerView.Adapter<*>
     private lateinit var viewManager: RecyclerView.LayoutManager
     private val programmeOfTheDay: ArrayList<Programme> = ArrayList()
-    private val day = arguments?.getString("day") ?: weekdays.first()
+
 
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
         // Inflate the layout for this fragment
+        val viewModel: ProgrammeDayViewModel = ViewModelProviders.of(this).get(ProgrammeDayViewModel::class.java)
+        viewModel.day = arguments?.getString("day") ?: ""
+
         val root = inflater.inflate(R.layout.fragment_programme_day, container, false)
         Planning.instance.programmes.forEach {
-            if (it.isThisDay(day = weekdays.indexOf(day)))
+            if (it.isThisDay(day = weekdays.indexOf(viewModel.day)))
                 programmeOfTheDay.add(it)
         }
         viewManager = LinearLayoutManager(context)
         viewAdapter =
-            ProgrammeAdapter(programmeOfTheDay, day)
+            ProgrammeAdapter(programmeOfTheDay, viewModel.day)
         recyclerView = root.findViewById<RecyclerView>(R.id.programme_recycler).apply {
             // use this setting to improve performance if you know that changes
             // in content do not change the layout size of the RecyclerView
         Planning.instance.currentProgramme.observe(viewLifecycleOwner,  Observer<String> {
             programmeOfTheDay.clear()
             Planning.instance.programmes.forEach {
-                if (it.isThisDay(day = weekdays.indexOf(day)))
+                if (it.isThisDay(day = weekdays.indexOf(viewModel.day)))
                     programmeOfTheDay.add(it)
             }
             viewAdapter.notifyDataSetChanged()

app/src/main/java/fr/forum_thalie/tsumugi/ui/programme/ProgrammeDayViewModel.kt

+package fr.forum_thalie.tsumugi.ui.programme
+
+import androidx.lifecycle.ViewModel
+
+class ProgrammeDayViewModel: ViewModel() {
+    var day: String = ""
+
+}