Fix crash on clicking "Go To Target" when selected trigger action has no parameters

Author: Rampastring

src/TSMapEditor/Constants.cs

@@ -4,7 +4,7 @@ namespace TSMapEditor
 {
     public static class Constants
     {
-        public const string ReleaseVersion = "1.7.2";
+        public const string ReleaseVersion = "1.7.3";
 
         public static int CellSizeX = 48;
         public static int CellSizeY = 24;

src/TSMapEditor/UI/Windows/TriggersWindow.cs

@@ -1156,6 +1156,9 @@ private void btnActionGoToTarget_LeftClick(object sender, EventArgs e)
             if (lbActions.SelectedItem == null)
                 return;
 
+            if (lbActionParameters.SelectedItem == null)
+                return;
+
             GetTriggerActionAndParamIndex(out TriggerAction triggerAction, out int paramIndex);            
 
             var triggerActionType = GetTriggerActionType(triggerAction.ActionIndex);