checkResult: Better output handling

The string was not setup properly, so the errorcode itself was not displayed correctly, and the new line was missing as well.
9 jobs for 54-checkresult-handle-error-output-better in 2 minutes and 10 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Lint
passed #3658
lint:lint-php5.4

00:00:45

passed #3659
lint:lint-php5.6

00:00:44

passed #3660
lint:lint-php7.0

00:00:45

passed #3661
lint:lint-php7.1

00:00:44

 
  Codesniffer
passed #3662
codesniffer

00:00:31

 
  Unit
passed #3663
unit:testBasic

00:00:51

passed #3664
unit:testRead

00:00:53

passed #3665
unit:testReadAssertFail

00:00:52

passed #3666
unit:testUserProperty

00:00:51