Aseprite export tags to sprite sheets (WebP)

Export Tags To Different Sprite Sheets.lua

-- Adapted from https://github.com/aseprite/Aseprite-Script-Examples/blob/68ed42647ef9990d6a27c4244277f83d6de8a69b/Export%20Tags%20To%20Different%20Sprite%20Sheets.lua
-- It worked great except that I prefer WebP. I added some more opinionated
-- changes while at it.
--
-- Changes include:
-- 1. WebP instead of PNG - Smaller, still supporting lossless and transparency
-- 2. Removed data generation - I don't need it
-- 3. Removed superfluous overwrite confirmation - Aseprite already asks
-- 4. Underscore separating file name - To fit my naming convention
-- 5. Lowercase tag in filename - Compatibility between OSs

-- Create a new RGB sprite based on the indexed sprite
local function createRGBSpriteFromIndexed(indexedSprite)
  -- Create a copy of the active sprite
  local rgbSprite = Sprite(indexedSprite)

  -- Set the color mode to RGB. Presumably none of the other settings matter in
  -- this use case (going to RGB)
  return pcall(function()
    app.command.ChangePixelFormat {
      format = "rgb",
      dithering = "",
      rgbmap = "default",
      toGray = "luma"
    }

    return rgbSprite
  end)
end

local function export(activeSprite)
  local success, rgbSprite = createRGBSpriteFromIndexed(activeSprite)

  if not success then
    print(string.format("Error in ChangePixelFormat: '%s'", result))
    return
  end

  local filename = activeSprite.filename:gsub("%.[^.]*$", "")

  for i, tag in ipairs(rgbSprite.tags) do
    local fn = filename .. '_' .. string.lower(tag.name) .. '.webp'

    local success, result = pcall(function()
      app.command.ExportSpriteSheet {
          ui = false,
          type = SpriteSheetType.HORIZONTAL,
          textureFilename = fn,
          tag = tag.name,
          listLayers = false,
          listTags = false,
          listSlices = false,
      }
    end)

    if not success then
      print(string.format(
        "Error in ExportSpriteSheet: '%s'. Tag name: '%s'",
        result, tag.name))
      break
    end
  end

  rgbSprite:close()
end

if not app.activeSprite then return end
export(app.activeSprite)