Fix crash when deleting the current skill set (#4772)

When removing it from table this causes crash when rebuilding skill set
dropdown.

Closes #4771

Signed-off-by: Tomas Slusny <ts6234@intl.att.com>

Signed-off-by: Tomas Slusny <ts6234@intl.att.com>
Co-authored-by: Tomas Slusny <ts6234@intl.att.com>

Author: deathbeam

src/Classes/SkillSetListControl.lua

@@ -100,7 +100,7 @@ function SkillSetListClass:OnSelDelete(index, skillSetId)
 	if #self.list > 1 then
 		main:OpenConfirmPopup("Delete Item Set", "Are you sure you want to delete '"..(skillSet.title or "Default").."'?", "Delete", function()
 			t_remove(self.list, index)
-			t_remove(self.skillsTab.skillSets, skillSetId)
+			self.skillsTab.skillSets[skillSetId] = nil
 			self.selIndex = nil
 			self.selValue = nil
 			if skillSetId == self.skillsTab.activeSkillSetId then
@@ -115,4 +115,4 @@ function SkillSetListClass:OnSelKeyDown(index, skillSetId, key)
 	if key == "F2" then
 		self:RenameSet(skillSetId)
 	end
-end
+end