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/ArchCure.cs

@@ -91,8 +91,6 @@ namespace Server.Spells.Fourth
                     }
                 }
             }
-
-            FinishSequence();
         }
 
         public override void OnCast()

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()

Projects/UOContent/Spells/Fourth/Curse.cs

@@ -101,8 +101,6 @@ namespace Server.Spells.Fourth
                     DoHurtFizzle();
                 }
             }
-
-            FinishSequence();
         }
 
         public override void OnCast()

Projects/UOContent/Spells/Fourth/FireField.cs

@@ -56,8 +56,6 @@ public class FireFieldSpell : MagerySpell, ISpellTargetingPoint3D
                 new FireFieldItem(itemID, targetLoc, Caster, Caster.Map, duration, i);
             }
         }
-
-        FinishSequence();
     }
 
     public override void OnCast()

Projects/UOContent/Spells/Fourth/GreaterHeal.cs

@@ -57,8 +57,6 @@ namespace Server.Spells.Fourth
                 m.FixedParticles(0x376A, 9, 32, 5030, EffectLayer.Waist);
                 m.PlaySound(0x202);
             }
-
-            FinishSequence();
         }
 
         public override bool CheckCast()

Projects/UOContent/Spells/Fourth/Lightning.cs

@@ -53,8 +53,6 @@ namespace Server.Spells.Fourth
 
                 SpellHelper.Damage(this, m, damage, 0, 0, 0, 0, 100);
             }
-
-            FinishSequence();
         }
 
         public override void OnCast()

Projects/UOContent/Spells/Fourth/ManaDrain.cs

@@ -73,8 +73,6 @@ namespace Server.Spells.Fourth
 
                 HarmfulSpell(m);
             }
-
-            FinishSequence();
         }
 
         public override void OnCast()

Projects/UOContent/Spells/Fourth/Recall.cs

@@ -101,8 +101,6 @@ namespace Server.Spells.Fourth
                 Caster.MoveToWorld(loc, map);
                 Caster.PlaySound(0x1FC);
             }
-
-            FinishSequence();
         }
 
         public override void GetCastSkills(out double min, out double max)
@@ -130,6 +128,7 @@ namespace Server.Spells.Fourth
             else
             {
                 Effect(m_Entry.Location, m_Entry.Map, true);
+                FinishSequence();
             }
         }