Fix the unknown texture error caused by a non-existent texture

[BingYanchi]

Because minecraft:item/white_stained_glass_pane does not exist, a texture error occurs. The fix is simple: just follow the format of Minecraft's assets.

white_stained_glass_pane.json extracted from Minecraft:

{
  "parent": "minecraft:item/generated",
  "textures": {
    "layer0": "minecraft:block/white_stained_glass"
  }
}