ST_Letters returns NULL all the time

[robe]

I was going to add some examples to manual and thought I would use ST_Letters, but it always returns NULL even using the example from the manual ​http://postgis.net/docs/manual-dev/ST_Letters.html

SELECT ST_Letters('Yo');

When I try the original from here: ​https://gist.githubusercontent.com/pramsey/2020ef463a8880edc7e23c56420d7df8/raw/dc53082cbe7c62e0a2eebf7ce32502576d281767/postgis_word.sql

SELECT ST_GeomFromWord('Yo');

that works.

[Regina Obe <lr@…>]

In 7324157/git:

Remove STRICT on postgis_letters (causes no font passed in to fail).
Closes #5085
Add some X3D examples that use letters