Вроде все ошибки устранил. не запускал.

PARR.AIHIT/AIHIT/Syncher.cs

@@ -25,7 +25,7 @@ namespace PARR.AIHIT
         private readonly IApplicationTypeService appTypeService;
         private readonly IApplicationInHostService appInHostService;
 
-        public List<ApplicationType> AppTypes { get; private set; }
+        public List<ApplicationType> AppTypes { get; private set; } = new List<ApplicationType>();
 
         public Syncher(
             ILogger<Syncher> logger,
@@ -332,7 +332,7 @@ namespace PARR.AIHIT
         {
             if (string.IsNullOrEmpty(appName)) return null;
 
-            var existApp = await appService.GetByName(appName);
+            var existApp = await appService.GetByNameAsync(appName);
             if (existApp != null)
                 return existApp;