fix: Fixes double calls with Target cancel and spell sequences (#1840)

### Summary
- Cleans up target cancellation being called incorrectly.
- An invalid target type (which should never happen), now calls `OnTargetUntargetable` instead of `OnTargetCanceled`
- Removes double calls to `FinishSequence` in Spells.

Projects/UOContent/Spells/Fourth/ArchProtection.cs

@@ -29,10 +29,14 @@ namespace Server.Spells.Fourth
 
         public void Target(IPoint3D p)
         {
+            if (Caster.Map == null)
+            {
+                return;
+            }
+
             if (CheckSequence())
             {
                 SpellHelper.Turn(Caster, p);
-
                 SpellHelper.GetSurfaceTop(ref p);
 
                 var loc = new Point3D(p);
@@ -42,12 +46,6 @@ namespace Server.Spells.Fourth
                     Effects.PlaySound(loc, Caster.Map, 0x299);
                 }
 
-                if (Caster.Map == null)
-                {
-                    FinishSequence();
-                    return;
-                }
-
                 using var targets = PooledRefQueue<Mobile>.Create();
                 foreach (var m in Caster.Map.GetMobilesInRange(loc, Core.AOS ? 2 : 3))
                 {
@@ -92,8 +90,6 @@ namespace Server.Spells.Fourth
                     }
                 }
             }
-
-            FinishSequence();
         }
 
         public override void OnCast()