Fix navigation bug

Fix a bug where pressing on multiple library items at once would cause a crash.

app/src/main/java/org/oxycblt/auxio/library/LibraryFragment.kt

@@ -46,6 +46,7 @@ class LibraryFragment : Fragment() {
 
     override fun onPause() {
         super.onPause()
+
         callback.isEnabled = false
     }
 

app/src/main/java/org/oxycblt/auxio/library/LibraryListFragment.kt

@@ -8,18 +8,22 @@ import android.view.ViewGroup
 import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.findNavController
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentLibraryListBinding
 import org.oxycblt.auxio.library.adapters.ArtistAdapter
 import org.oxycblt.auxio.music.MusicViewModel
+import org.oxycblt.auxio.music.models.Artist
 import org.oxycblt.auxio.recycler.ClickListener
 import org.oxycblt.auxio.recycler.applyDivider
 
 class LibraryListFragment : Fragment() {
 
-    private val musicModel: MusicViewModel by activityViewModels {
-        MusicViewModel.Factory(requireActivity().application)
+    private val musicModel: MusicViewModel by activityViewModels()
+
+    private val libraryModel: LibraryViewModel by lazy {
+        ViewModelProvider(this).get(LibraryViewModel::class.java)
     }
 
     override fun onCreateView(
@@ -33,11 +37,7 @@ class LibraryListFragment : Fragment() {
 
         binding.libraryRecycler.adapter = ArtistAdapter(
             musicModel.artists.value!!,
-            ClickListener { artist ->
-                findNavController().navigate(
-                    LibraryListFragmentDirections.actionShowArtist(artist.id)
-                )
-            }
+            ClickListener { navToArtist(it) }
         )
         binding.libraryRecycler.applyDivider()
         binding.libraryRecycler.setHasFixedSize(true)
@@ -46,4 +46,21 @@ class LibraryListFragment : Fragment() {
 
         return binding.root
     }
+
+    override fun onPause() {
+        super.onPause()
+
+        libraryModel.isAlreadyNavigating = false
+    }
+
+    private fun navToArtist(artist: Artist) {
+        // Don't navigate to a fragment multiple times if multiple items are accepted.
+        if (!libraryModel.isAlreadyNavigating) {
+            libraryModel.isAlreadyNavigating = true
+
+            findNavController().navigate(
+                LibraryListFragmentDirections.actionShowArtist(artist.id)
+            )
+        }
+    }
 }

app/src/main/java/org/oxycblt/auxio/library/LibraryViewModel.kt

@@ -0,0 +1,7 @@
+package org.oxycblt.auxio.library
+
+import androidx.lifecycle.ViewModel
+
+class LibraryViewModel : ViewModel() {
+    var isAlreadyNavigating = false
+}