explain purpose

1 job for master in 18 minutes and 26 seconds (queued for 1 second)
Name Stage Failure
build Build
Updating HTML index of packages in '.Library'
There were 11 warnings (use warnings() to see them)
Error in loadNamespace(name) : there is no package called 'devtools'
Calls: :: ... loadNamespace -> withRestarts -> withOneRestart -> doWithOneRestart
Execution halted
error building image: error building stage: failed to execute command: waiting for process to exit: exit status 1
Cleaning up file based variables
ERROR: Job failed: exit code 1