imageBlurhash is set to null by updatePost when image missing

[AustenLamacraft]

If you edit a post and trigger updatePost then the data sent

      data: {
        title,
        description,
        content,
        slug,
        image,
        imageBlurhash: await getBlurDataURL(image),
        published,
      }

has no image so imageBlurhash ends up being null and gets updated accordingly, causing an error. I found that

      data: {
        title,
        description,
        content,
        slug,
        image,
        imageBlurhash: (await getBlurDataURL(image)) ?? undefined,
        published,
      }

fixes the problem