Validate imageSizes.formatOptions.format against mimeTypes in Uploads config

[PatrikKozak]

Currently, when defining imageSizes in an upload config, there’s no validation against the mimeTypes array in the collection config. This can lead to a situation where an invalid image format is used in imageSizes, but the error only appears at runtime when attempting to upload a file.

For example:

upload: {
  mimeTypes: ['image/png', 'image/jpeg'], // Does not include webp
  imageSizes: [
    {
      name: 'small',
      formatOptions: {
        format: 'webp', // This will cause an error at runtime
      },
      width: 800,
    },
  ],
}

In this case, the config is invalid, but the issue is only caught when an upload happens.

Proposed changes

• Add validation at startup to check if any format specified in imageSizes is missing from mimeTypes.
• If a mismatch is found, throw an error at build time with a message like:

"Found 'webp' in imageSizes, but it's missing from mimeTypes. Add 'image/webp' to mimeTypes to allow this format."

Considerations

• This would prevent misconfiguration from going unnoticed until runtime.
• If mimeTypes is undefined, no validation should occur, since the field is unrestricted.