Fix NPE from facing being null when drawing grid overlays (#2401)

(cherry picked from commit ae5ef98)

src/main/java/gregtech/common/ToolEventHandlers.java

@@ -477,6 +477,8 @@ private static void drawGridOverlays(@NotNull AxisAlignedBB box) {
 
     @SideOnly(Side.CLIENT)
     private static void drawGridOverlays(EnumFacing facing, AxisAlignedBB box, Predicate<EnumFacing> test) {
+        if (facing == null) return;
+
         Tessellator tessellator = Tessellator.getInstance();
         BufferBuilder buffer = tessellator.getBuffer();
         buffer.begin(3, DefaultVertexFormats.POSITION_COLOR);