• You can reduce space by set Use Compression and change Output as Image String when using the Espruino Image Converter

  • Edit: did not read the reply from Gordon.
    It seems that my file is still too big.

    That's not it.
    I changed all images to test:

    var imgNewMoon = {
      width : 26, height : 26, bpp : 1,
      transparent : 0,
      buffer : require("heatshrink").decompress(atob("A­H4AUA=="))

    They are much shorter now, but I still receive the same error.