Resolve Vault and DB Warnings (#4646)

* Resolve Vault Warnings

* Resolve DB Warnings

src/Api/Vault/AuthorizationHandlers/Collections/BulkCollectionAuthorizationHandler.cs

@@ -1,4 +1,5 @@
 #nullable enable
+using System.Diagnostics;
 using Bit.Core.Context;
 using Bit.Core.Entities;
 using Bit.Core.Enums;
@@ -98,6 +99,12 @@ public class BulkCollectionAuthorizationHandler : BulkAuthorizationHandler<BulkC
             case not null when requirement == BulkCollectionOperations.Delete:
                 authorized = await CanDeleteAsync(resources, org);
                 break;
+
+            case null:
+                // requirement isn't actually nullable but since we use the 
+                // not null when trick it makes the compiler think that requirement
+                // could actually be nullable.
+                throw new UnreachableException();
         }
 
         if (authorized)

src/Api/Vault/Models/Response/OptionalCipherDetailsResponseModel.cs

@@ -1,6 +1,8 @@
 using Bit.Api.Vault.Models.Response;
 using Bit.Core.Models.Api;
 
+#nullable enable
+
 public class OptionalCipherDetailsResponseModel : ResponseModel
 {
     public bool Unavailable { get; set; }