Running composer to install a new package locally caused the following error:
PHP Fatal error: Allowed memory size of 1610612736 bytes exhausted (tried to allocate 4096 bytes) in phar:///usr/local/bin/composer/src/Composer/DependencyResolver/Solver.php on line 223
The solution was to allow my local setup to consume as much memory as it needs to run:
php -d memory_limit=-1 /usr/local/bin/composer require --dev knuckleswtf/scribe