Revert "don't throw exception on unpublished sheets"

This reverts commit 6becdb1.

Mimir.Worker/Initializer/TableSheetInitializer.cs

@@ -93,8 +93,7 @@ private static async Task SyncSheetStateAsync(
         var sheetState = await stateService.GetState(sheetAddress, stoppingToken);
         if (sheetState is not Text sheetValue)
         {
-            logger.Error("Expected sheet state of {SheetTypeName} to be of type {TextType}", sheetType.Name, typeof(Text));
-            return;
+            throw new InvalidCastException($"Expected sheet state to be of type 'Text'.");
         }
 
         sheet.Set(sheetValue.Value);