Error message

• Notice: Trying to get property of non-object in autocar_custom_ds_field_author_with_image_and_post_date() (line 790 of /var/www/haymarket/d7automotive/sites/autocar.co.uk/modules/custom/autocar_custom/autocar_custom.module).
• Notice: Trying to get property of non-object in autocar_custom_ds_field_author_with_image_and_post_date() (line 792 of /var/www/haymarket/d7automotive/sites/autocar.co.uk/modules/custom/autocar_custom/autocar_custom.module).
• Notice: Trying to get property of non-object in autocar_custom_ds_field_author_with_image_and_post_date() (line 803 of /var/www/haymarket/d7automotive/sites/autocar.co.uk/modules/custom/autocar_custom/autocar_custom.module).
• Notice: Trying to get property of non-object in autocar_custom_ds_field_author_with_image_and_post_date() (line 805 of /var/www/haymarket/d7automotive/sites/autocar.co.uk/modules/custom/autocar_custom/autocar_custom.module).
• Notice: Undefined index: uri in theme_image_formatter() (line 602 of /var/www/haymarket/d7automotive/modules/image/image.field.inc).