Fix INVALID_REF errors caused by mods (R2Northstar#657)

`INVALID_REF` errors were being caused by trying to get the item image for weapon skins.

If a mod (e.g. moreskins) added new skins, the client equipped one, and then the mod is disabled, the client now has bad persistence.
This is mostly handled fine by the game, except for weapon skins. This PR prevents the crash, and resets the bad persistence to default.

Northstar.Client/mod/scripts/vscripts/ui/menu_edit_pilot_loadouts.nut

@@ -0,0 +1,170 @@
+untyped
+
+global function InitEditPilotLoadoutsMenu
+
+struct
+{
+	var menu
+	var loadoutPanel
+	var[NUM_PERSISTENT_PILOT_LOADOUTS] loadoutHeaders
+	var[NUM_PERSISTENT_PILOT_LOADOUTS] activateButtons
+	bool enteringEdit = false
+	var unlockReq
+} file
+
+void function InitEditPilotLoadoutsMenu()
+{
+	file.menu = GetMenu( "EditPilotLoadoutsMenu" )
+	var menu = file.menu
+
+	AddMenuEventHandler( menu, eUIEvent.MENU_OPEN, OnPilotLoadoutsMenu_Open )
+	AddMenuEventHandler( menu, eUIEvent.MENU_CLOSE, OnPilotLoadoutsMenu_Close )
+	AddMenuEventHandler( menu, eUIEvent.MENU_INPUT_MODE_CHANGED, OnPilotLoadoutsMenu_InputModeChanged )
+
+	for ( int i = 0; i < NUM_PERSISTENT_PILOT_LOADOUTS; i++ )
+	{
+		var activateButton = Hud_GetChild( menu, "Button" + i )
+		activateButton.s.rowIndex <- i
+		Hud_SetVisible( activateButton, true )
+		Hud_AddEventHandler( activateButton, UIE_CLICK, OnLoadoutButton_Activate )
+		Hud_AddEventHandler( activateButton, UIE_GET_FOCUS, OnLoadoutButton_Focused )
+		Hud_AddEventHandler( activateButton, UIE_LOSE_FOCUS, OnLoadoutButton_LostFocus )
+		file.activateButtons[i] = activateButton
+	}
+
+	Hud_SetFocused( file.activateButtons[0] )
+
+	file.loadoutPanel = Hud_GetChild( menu, "PilotLoadoutDisplay" )
+	file.unlockReq = Hud_GetChild( menu, "UnlockReq" )
+
+	AddMenuFooterOption( menu, BUTTON_A, "#A_BUTTON_SELECT" )
+	AddMenuFooterOption( menu, BUTTON_B, "#B_BUTTON_BACK", "#BACK" )
+}
+
+void function OnPilotLoadoutsMenu_Open()
+{
+	entity player = GetUIPlayer()
+	if ( player == null )
+		return
+
+	RunMenuClientFunction( "ClearEditingPilotLoadoutIndex" )
+
+	int loadoutIndex = uiGlobal.pilotSpawnLoadoutIndex
+	UpdatePilotLoadoutButtons( loadoutIndex, file.activateButtons )
+	UpdatePilotLoadoutPanel( file.loadoutPanel, GetCachedPilotLoadout( loadoutIndex ) )
+	UI_SetPresentationType( ePresentationType.PILOT )
+
+	RefreshCreditsAvailable()
+}
+
+void function OnPilotLoadoutsMenu_Close()
+{
+	entity player = GetUIPlayer()
+	if ( player == null )
+		return
+
+	foreach ( i, button in file.activateButtons )
+	{
+		string pilotLoadoutRef = "pilot_loadout_" + ( i + 1 )
+		if ( !IsItemNew( player, pilotLoadoutRef ) )
+			continue
+
+		ClearNewStatus( button, pilotLoadoutRef )
+	}
+}
+
+void function OnPilotLoadoutsMenu_InputModeChanged()
+{
+	UpdatePilotLoadoutPanelBinds( file.loadoutPanel )
+}
+
+void function OnLoadoutButton_Focused( var button )
+{
+	int index = expect int( button.s.rowIndex )
+
+	// update the editingLoadoutIndex on focus so that it always matches
+	// with the pilot loadout panel
+	uiGlobal.editingLoadoutIndex = index
+	uiGlobal.editingLoadoutType = "pilot"
+
+	UpdatePilotLoadout( index )
+
+	string pilotLoadoutRef = "pilot_loadout_" + ( index + 1 )
+	string unlockReq = GetItemUnlockReqText( pilotLoadoutRef )
+	RHud_SetText( file.unlockReq, unlockReq )
+}
+
+void function UpdatePilotLoadout( int loadoutIndex )
+{
+	PilotLoadoutDef loadout = GetCachedPilotLoadout( loadoutIndex )
+
+	UpdatePilotLoadoutPanel( file.loadoutPanel, loadout )
+	RunMenuClientFunction( "UpdatePilotModel", loadoutIndex )
+}
+
+void function OnLoadoutButton_Activate( var button )
+{
+	if ( !IsFullyConnected() )
+		return
+
+	if ( Hud_IsLocked( button ) )
+	{
+		int index = expect int ( button.s.rowIndex )
+		string pilotLoadoutRef = "pilot_loadout_" + ( index + 1 )
+
+		array<var> buttons
+		foreach ( button in file.activateButtons )
+		{
+			buttons.append( button )
+		}
+
+		OpenBuyItemDialog( buttons, button, GetItemName( pilotLoadoutRef ), pilotLoadoutRef )
+		return
+	}
+
+	int loadoutIndex = expect int ( button.s.rowIndex )
+	SetEditLoadout( "pilot", loadoutIndex )
+
+	if ( EDIT_LOADOUT_SELECTS )
+	{
+		bool indexChanged = loadoutIndex != uiGlobal.pilotSpawnLoadoutIndex
+
+		if ( indexChanged )
+		{
+			EmitUISound( "Menu_LoadOut_Pilot_Select" )
+
+			if ( !IsLobby() )
+				uiGlobal.updatePilotSpawnLoadout = true
+		}
+
+		uiGlobal.pilotSpawnLoadoutIndex = loadoutIndex
+		ClientCommand( "RequestPilotLoadout " + loadoutIndex )
+	}
+
+	if ( PRE_RELEASE_DEMO && loadoutIndex < 3 )
+	{
+		UpdatePilotLoadoutButtons( loadoutIndex, file.activateButtons )
+		return
+	}
+
+	RunMenuClientFunction( "SetEditingPilotLoadoutIndex", loadoutIndex )
+	AdvanceMenu( GetMenu( "EditPilotLoadoutMenu" ) )
+}
+
+void function OnLoadoutButton_LostFocus( var button )
+{
+	entity player = GetUIPlayer()
+	if ( !IsValid( player ) )
+		return
+
+	int loadoutIndex = expect int ( button.s.rowIndex )
+	string pilotLoadoutRef = "pilot_loadout_" + ( loadoutIndex + 1 )
+	ClearNewStatus( button, pilotLoadoutRef )
+
+	if ( IsItemLocked( player, pilotLoadoutRef ) )
+		return
+
+	PilotLoadoutDef loadout = GetCachedPilotLoadout( loadoutIndex )
+	if ( (RefHasAnyNewSubitem( player, loadout.primary ) || RefHasAnyNewSubitem( player, loadout.secondary ) || RefHasAnyNewSubitem( player, loadout.weapon3 )) )
+		Hud_SetNew( button, true )
+}