Fix rare bug in FORCE_CHANCE_TO_HIT

If in attack end in FORCE_CHANCE_TO_HIT macro, unit or second unit doesn't exist anymore because rare case where unit disapear before attack end event was calledthen we have an error message like "Invalid WML found: [unstore_unit]: variable 'second_unit' doesn't exist" because presence of unit not condition of execution of event.

data/core/macros/utils.cfg

@@ -514,6 +514,8 @@
     #!         greater_than=10
     #!     [/variable]
     #! )}
+    # WARNING : if an unit must disappear in mid-battle before attack end was fired, recreate unit instead to unstore or cth modifications
+    # persist. Or don't use this macro.
     [event]
         name=attack
         first_time_only=no
@@ -564,6 +566,9 @@
                         id=forced_cth
                         value={CTH_NUMBER}
                         cumulative=no
+                        [filter_opponent]
+                            {SECOND_FILTER}
+                        [/filter_opponent]
                     [/value]
                 [/set_variables]
             [/do]
@@ -578,6 +583,12 @@
             name=attack end
             delayed_variable_substitution=yes
 
+            [filter_condition]
+                [have_unit]
+                    id=$unit.id
+                [/have_unit]
+            [/filter_condition]
+
             [foreach]
                 array=unit.attack
                 [do]
@@ -651,6 +662,9 @@
                         id=forced_cth
                         value={CTH_NUMBER}
                         cumulative=no
+                        [filter_opponent]
+                            {SECOND_FILTER}
+                        [/filter_opponent]
                     [/value]
                 [/set_variables]
             [/do]
@@ -665,6 +679,12 @@
             name=attack end
             delayed_variable_substitution=yes
 
+            [filter_condition]
+                [have_unit]
+                    id=$second_unit.id
+                [/have_unit]
+            [/filter_condition]
+
             [foreach]
                 array=second_unit.attack
                 [do]

data/scenario-test.cfg

@@ -4063,6 +4063,35 @@ unplagueable: $wml_unit.status.unplagueable"
         {CLEAR_VARIABLE x_len}
         {CLEAR_VARIABLE xy_len}
     [/event]
+    {FORCE_CHANCE_TO_HIT (type=Silver Mage) (type="Orcish Archer") 50 ()}
+    [event]
+        name=attack end
+        [filter]
+            type=Silver Mage
+        [/filter]
+
+       [store_unit]
+	    [filter]
+                id=$unit.id
+	    [/filter]
+		variable=blink_test
+		kill=yes
+	[/store_unit]
+    [/event]
+    [event]
+	name=turn 2
+	[unstore_unit]
+		variable=blink_test
+		x,y=17,3
+	[/unstore_unit]
+	[unit]
+		side=2
+		x,y=18,3
+		type="Orcish Archer"
+		generate_name=yes
+		jamming=5
+	[/unit]
+[/event]
 [/test]
 
 [units]