Issue with returning null value for blurhash in image schema resolved with help from Geoff.

*[_type == "homePage"] | order(_updatedAt desc) [0] {
  sections[] {
    ...,
    _type == "contentImage" => {
      ...,
      image {
        ...,
        "height": asset->metadata.dimensions.height,
        "width": asset->metadata.dimensions.width,
        "dimensions": asset->metadata.dimensions,
        "blurhash": asset->metadata.blurHash,
        "lqip": asset->metadata.lqip
      }
    }
  }
}

export default {
  title: 'Image',
  name: 'picture',
  type: 'image',
  icon: ImageSquare,
  options: {
    hotspot: true,
    metadata: ['lqip', 'blurhash']
  },
  fields: [
    {
      title: 'Alternative Text',
      name: 'alt',
      type: 'string',
      description: 'A short description of the image. Important for SEO and accessiblity.',
      validation: (Rule) => Rule.required()
    },
    {
      title: 'Display Size (Aspect Ratio)',
      name: 'customRatio',
      type: 'string',
      description: 'Select how the image is displayed. This affects the aspect ratio of the image within its container.',
      options: {
        list: aspectRatios
      },
      initialValue: 'aspect-0'
    }
  ],
  preview: {
    select: {
      alt: 'alt',
      filename: 'asset.originalFilename',
      dimensions: 'asset.metadata.dimensions',
      image: 'asset'
    },
    prepare({ alt, dimensions, filename, image }) {
      return {
        title: alt ?? filename,
        subtitle: dimensions ? `${dimensions.width}px × ${dimensions.height}px` : '…',
        media: image ?? ImageSquare
      }
    }
  }
}