Avoid crashing in SourcePreferencesFragment if source can't be loaded

Should probably wait for sources to definitely be loaded first, but that's
sort of a bigger change and needs to be lifecycle-aware.

app/src/main/java/eu/kanade/tachiyomi/ui/browse/extension/details/SourcePreferencesScreen.kt

@@ -65,8 +65,7 @@ class SourcePreferencesScreen(val sourceId: Long) : Screen() {
                     .fillMaxSize()
                     .padding(contentPadding),
             ) {
-                val fragment = SourcePreferencesFragment.getInstance(sourceId)
-                add(it, fragment, null)
+                add(it, SourcePreferencesFragment.getInstance(sourceId), null)
             }
         }
     }
@@ -127,26 +126,28 @@ class SourcePreferencesFragment : PreferenceFragmentCompat() {
 
     private fun populateScreen(): PreferenceScreen {
         val sourceId = requireArguments().getLong(SOURCE_ID)
-        val source = Injekt.get<SourceManager>().get(sourceId)!! as ConfigurableSource
+        val source = Injekt.get<SourceManager>().getOrStub(sourceId)
+        val sourceScreen = preferenceManager.createPreferenceScreen(requireContext())
 
-        val dataStore = SharedPreferencesDataStore(source.sourcePreferences())
-        preferenceManager.preferenceDataStore = dataStore
+        if (source is ConfigurableSource) {
+            val dataStore = SharedPreferencesDataStore(source.sourcePreferences())
+            preferenceManager.preferenceDataStore = dataStore
 
-        val sourceScreen = preferenceManager.createPreferenceScreen(requireContext())
-        source.setupPreferenceScreen(sourceScreen)
-        sourceScreen.forEach { pref ->
-            pref.isIconSpaceReserved = false
-            pref.isSingleLineTitle = false
-            if (pref is DialogPreference && pref.dialogTitle.isNullOrEmpty()) {
-                pref.dialogTitle = pref.title
-            }
+            source.setupPreferenceScreen(sourceScreen)
+            sourceScreen.forEach { pref ->
+                pref.isIconSpaceReserved = false
+                pref.isSingleLineTitle = false
+                if (pref is DialogPreference && pref.dialogTitle.isNullOrEmpty()) {
+                    pref.dialogTitle = pref.title
+                }
 
-            // Apply incognito IME for EditTextPreference
-            if (pref is EditTextPreference) {
-                val setListener = pref.getOnBindEditTextListener()
-                pref.setOnBindEditTextListener {
-                    setListener?.onBindEditText(it)
-                    it.setIncognito(lifecycleScope)
+                // Apply incognito IME for EditTextPreference
+                if (pref is EditTextPreference) {
+                    val setListener = pref.getOnBindEditTextListener()
+                    pref.setOnBindEditTextListener {
+                        setListener?.onBindEditText(it)
+                        it.setIncognito(lifecycleScope)
+                    }
                 }
             }
         }
@@ -158,9 +159,9 @@ class SourcePreferencesFragment : PreferenceFragmentCompat() {
         private const val SOURCE_ID = "source_id"
 
         fun getInstance(sourceId: Long): SourcePreferencesFragment {
-            val fragment = SourcePreferencesFragment()
-            fragment.arguments = bundleOf(SOURCE_ID to sourceId)
-            return fragment
+            return SourcePreferencesFragment().apply {
+                arguments = bundleOf(SOURCE_ID to sourceId)
+            }
         }
     }
 }