`preamble-trim`

There is no extra whitespace around preamble fields.

Examples

error[preamble-trim]: preamble header `description` has extra whitespace
 --> input.md:3:13
  |
3 | description: Also missing 
  |             ^^^^^^^^^^^^^^ value has extra whitespace
  |

Explanation

preamble-trim ensures that front matter (or preamble) field values don't have extra whitespace.