Build task fails on project without composer.json file

Migrated issue

Reported by: grimreaper

Related to !323 (merged) !322 (merged)

Problem/Motivation

On a project withou a composer.json file, the build task fails like on https://git.drupalcode.org/project/ui_examples/-/jobs/4167498

$ rm $_WEB_ROOT/modules/custom/$CI_PROJECT_NAME/composer.json # collapsed multi-line command
rm: cannot remove 'web/modules/custom/ui_examples/composer.json': No such file or directory

Steps to reproduce

Proposed resolution

Add optional removal.