Avoid crashing if opening browse with unavailable source

app/src/main/java/eu/kanade/tachiyomi/source/SourceManager.kt

@@ -152,6 +152,6 @@ class SourceManager(
         }
     }
 
-    inner class SourceNotInstalledException(val sourceString: String) :
+    inner class SourceNotInstalledException(sourceString: String) :
         Exception(context.getString(R.string.source_not_installed, sourceString))
 }

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/BrowseSourceScreen.kt

@@ -39,6 +39,7 @@ import cafe.adriel.voyager.core.screen.uniqueScreenKey
 import cafe.adriel.voyager.navigator.LocalNavigator
 import cafe.adriel.voyager.navigator.currentOrThrow
 import eu.kanade.presentation.browse.BrowseSourceContent
+import eu.kanade.presentation.browse.MissingSourceScreen
 import eu.kanade.presentation.browse.components.BrowseSourceToolbar
 import eu.kanade.presentation.browse.components.RemoveMangaDialog
 import eu.kanade.presentation.components.ChangeCategoryDialog
@@ -48,7 +49,9 @@ import eu.kanade.presentation.components.Scaffold
 import eu.kanade.presentation.util.AssistContentScreen
 import eu.kanade.presentation.util.padding
 import eu.kanade.tachiyomi.R
+import eu.kanade.tachiyomi.source.CatalogueSource
 import eu.kanade.tachiyomi.source.LocalSource
+import eu.kanade.tachiyomi.source.SourceManager
 import eu.kanade.tachiyomi.source.online.HttpSource
 import eu.kanade.tachiyomi.ui.browse.source.browse.BrowseSourceScreenModel.Listing
 import eu.kanade.tachiyomi.ui.category.CategoryScreen
@@ -73,17 +76,10 @@ data class BrowseSourceScreen(
 
     @Composable
     override fun Content() {
-        val navigator = LocalNavigator.currentOrThrow
-        val scope = rememberCoroutineScope()
-        val context = LocalContext.current
-        val haptic = LocalHapticFeedback.current
-        val uriHandler = LocalUriHandler.current
-
         val screenModel = rememberScreenModel { BrowseSourceScreenModel(sourceId, listingQuery) }
         val state by screenModel.state.collectAsState()
 
-        val snackbarHostState = remember { SnackbarHostState() }
-
+        val navigator = LocalNavigator.currentOrThrow
         val navigateUp: () -> Unit = {
             when {
                 !state.isUserQuery && state.toolbarQuery != null -> screenModel.setToolbarQuery(null)
@@ -91,8 +87,21 @@ data class BrowseSourceScreen(
             }
         }
 
-        val onHelpClick = { uriHandler.openUri(LocalSource.HELP_URL) }
+        if (screenModel.source is SourceManager.StubSource) {
+            MissingSourceScreen(
+                source = screenModel.source,
+                navigateUp = navigateUp,
+            )
+            return
+        }
 
+        val scope = rememberCoroutineScope()
+        val context = LocalContext.current
+        val haptic = LocalHapticFeedback.current
+        val uriHandler = LocalUriHandler.current
+        val snackbarHostState = remember { SnackbarHostState() }
+
+        val onHelpClick = { uriHandler.openUri(LocalSource.HELP_URL) }
         val onWebViewClick = f@{
             val source = screenModel.source as? HttpSource ?: return@f
             navigator.push(
@@ -147,7 +156,7 @@ data class BrowseSourceScreen(
                                 Text(text = stringResource(R.string.popular))
                             },
                         )
-                        if (screenModel.source.supportsLatest) {
+                        if ((screenModel.source as CatalogueSource).supportsLatest) {
                             FilterChip(
                                 selected = state.listing == Listing.Latest,
                                 onClick = {

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/BrowseSourceScreenModel.kt

@@ -103,23 +103,25 @@ class BrowseSourceScreenModel(
 
     var displayMode by sourcePreferences.sourceDisplayMode().asState(coroutineScope)
 
-    val source = sourceManager.get(sourceId) as CatalogueSource
+    val source = sourceManager.getOrStub(sourceId)
 
     init {
-        mutableState.update {
-            var query: String? = null
-            var listing = it.listing
+        if (source is CatalogueSource) {
+            mutableState.update {
+                var query: String? = null
+                var listing = it.listing
 
-            if (listing is Listing.Search) {
-                query = listing.query
-                listing = Listing.Search(query, source.getFilterList())
+                if (listing is Listing.Search) {
+                    query = listing.query
+                    listing = Listing.Search(query, source.getFilterList())
+                }
+
+                it.copy(
+                    listing = listing,
+                    filters = source.getFilterList(),
+                    toolbarQuery = query,
+                )
             }
-
-            it.copy(
-                listing = listing,
-                filters = source.getFilterList(),
-                toolbarQuery = query,
-            )
         }
     }
 
@@ -164,6 +166,8 @@ class BrowseSourceScreenModel(
     }
 
     fun resetFilters() {
+        if (source !is CatalogueSource) return
+
         mutableState.update { it.copy(filters = source.getFilterList()) }
     }
 
@@ -172,6 +176,8 @@ class BrowseSourceScreenModel(
     }
 
     fun search(query: String? = null, filters: FilterList? = null) {
+        if (source !is CatalogueSource) return
+
         val input = state.value.listing as? Listing.Search
             ?: Listing.Search(query = null, filters = source.getFilterList())
 
@@ -187,6 +193,8 @@ class BrowseSourceScreenModel(
     }
 
     fun searchGenre(genreName: String) {
+        if (source !is CatalogueSource) return
+
         val defaultFilters = source.getFilterList()
         var genreExists = false