Fix some crashes due to bad UI state (#617)

## Description
Fixes two possible crashes:
- When saving view options for a favorite page tab
- When there are no results on a grid page/tab

app/src/main/java/com/github/damontecres/wholphin/ui/components/CollectionFolderGrid.kt

@@ -169,6 +169,7 @@ class CollectionFolderViewModel
                     context.getString(R.string.error_loading_collection, itemId),
                 ) + Dispatchers.IO,
             ) {
+                super.itemId = itemId
                 itemId.toUUIDOrNull()?.let {
                     fetchItem(it)
                 }
@@ -206,7 +207,7 @@ class CollectionFolderViewModel
         ) {
             if (collectionFilter.useSavedLibraryDisplayInfo) {
                 serverRepository.currentUser.value?.let { user ->
-                    viewModelScope.launch(Dispatchers.IO) {
+                    viewModelScope.launchIO {
                         val libraryDisplayInfo =
                             LibraryDisplayInfo(
                                 userId = user.rowId,

app/src/main/java/com/github/damontecres/wholphin/ui/detail/CardGrid.kt

@@ -196,6 +196,19 @@ fun <T : CardGridItem> CardGrid(
         }
     }
 
+    if (pager.isEmpty()) {
+        Box(
+            contentAlignment = Alignment.Center,
+            modifier = modifier.fillMaxSize(),
+        ) {
+            Text(
+                text = stringResource(R.string.no_results),
+                style = MaterialTheme.typography.titleLarge,
+                color = MaterialTheme.colorScheme.onSurface,
+                textAlign = TextAlign.Center,
+            )
+        }
+    } else {
         var longPressing by remember { mutableStateOf(false) }
         Row(
 //        horizontalArrangement = Arrangement.spacedBy(8.dp),
@@ -403,6 +416,7 @@ fun <T : CardGridItem> CardGrid(
             }
         }
     }
+}
 
 @Composable
 fun JumpButtons(

app/src/main/java/com/github/damontecres/wholphin/ui/detail/ItemViewModel.kt

@@ -27,7 +27,7 @@ abstract class ItemViewModel(
 ) : ViewModel() {
     val item = MutableLiveData<BaseItem?>(null)
     lateinit var itemId: String
-    lateinit var itemUuid: UUID
+    var itemUuid: UUID? = null
 
     suspend fun fetchItem(itemId: UUID): BaseItem =
         withContext(Dispatchers.IO) {

app/src/main/java/com/github/damontecres/wholphin/ui/detail/PersonPage.kt

@@ -155,8 +155,10 @@ class PersonViewModel
 
         fun setFavorite(favorite: Boolean) {
             viewModelScope.launchIO {
-                favoriteWatchManager.setFavorite(itemUuid, favorite)
-                fetchAndSetItem(itemUuid)
+                itemUuid?.let {
+                    favoriteWatchManager.setFavorite(it, favorite)
+                    fetchAndSetItem(it)
+                }
             }
         }
     }