Function key_image_exists 

pub fn key_image_exists(
    key_image: &KeyImage,
    table_key_images: &impl DatabaseRo<KeyImages>,
) -> DbResult<bool>

Check if a KeyImage exists - i.e. if it is “spent”.

Errors

This function returns cuprate_database::RuntimeError::KeyNotFound if the input (if applicable) doesn’t exist or other RuntimeError’s on database errors.