Grunt fail due to no syntax error

[bappa-ww]

The grunt task . is failing due to no syntax error. Please find below message

Running "phplint:all" (phplint) task
Warning: No syntax errors detected in <_A_FILE.PHP_> Use --force to continue.

Aborted due to warnings.

I feel like even no warning output to stdout and grunt finds it a warning and exit(). Please help.