Only renders the git icon if the icon is not empty (#633)

lua/nvim-tree/renderer.lua

@@ -231,9 +231,11 @@ if icon_state.show_git_icon then
       icons = git_icon_state.dirty
     end
     for _, v in ipairs(icons) do
+      if #v.icon > 0 then
         table.insert(hl, { v.hl, line, depth+icon_len+#icon, depth+icon_len+#icon+#v.icon })
         icon = icon..v.icon..icon_padding
       end
+    end
 
     return icon
   end