How to access first image from array in Sanity preview select syntax?

Looking at your code, you're very close! The syntax for accessing array items in Sanity's preview select is to use dot notation with the index number, like 'vehicleContent.bilder.0' instead of 'vehicleContent.bilder[0]'.

Here's your corrected preview config:

preview: {
  select: {
    status: 'vehicleContent.synlighet.status',
    modelName: 'vehicleContent.typeinfo.modellbetegnelse',
    licensePlate: 'vehicleContent.identitet.licensePlate',
    manufac: 'vehicleContent.typeinfo.manufacturer.label',
    heroImage: 'vehicleContent.bilder.0',  // Changed from [0] to .0
    year: 'vehicleContent.datoer.FirstRegisterDate'
  },
  prepare({status, heroImage, modelName, year, licensePlate, manufac}) {
    return {
      media: heroImage,  // Remove the template literal - just pass the value directly
      title: `${licensePlate}  -  ${status.toUpperCase()}`,
      subtitle: `${year ? year.split('-')[0] : ''} ${manufac ? manufac : ''} ${modelName ? modelName : ''}`
    }
  }
}

Two key changes:

1. Array index syntax: Use 'vehicleContent.bilder.0' with dot notation rather than bracket notation [0]. This is the standard way to access array items in preview configuration.

2. Media value: Pass heroImage directly instead of wrapping it in a template literal (${heroImage}). The media property expects the actual image object, not a string representation of it.

If your image field is an image type with an asset reference, you might also want to be more specific and use 'vehicleContent.bilder.0.asset' to directly access the asset, though often just .0 works fine depending on your schema structure.