Pseudo pattern jsons starting with digits gives PHP warnings #114
Description
sample warning:
Pseudo pattern filename was something like 000-page-header~phone.json:
PHP Warning: file_get_contents(/.../pattern-lab/../source/_patterns/02-molecules/page-header/000-page-header.twig): failed to open stream: No such file or directory in /.../pattern-lab/vendor/pattern-lab/core/src/PatternLab/Builder.php on line 223
Warning: file_get_contents(/.../pattern-lab/../source/_patterns/02-molecules/page-header/000-page-header.twig): failed to open stream: No such file or directory in /.../pattern-lab/vendor/pattern-lab/core/src/PatternLab/Builder.php on line 223