fatal: [vagrant]: FAILED! => {"changed": true, "cmd": ["yarn", "build"], "delta": "0:00:08.264017", "end": "2018-06-14 10:51:11.149753", "failed": true, "msg": "non-zero return code", "rc": 1, "start": "2018-06-14 10:51:02.885736", "stderr": "[10:51:05] Failed to load external module @babel/register\nFontconfig warning: ignoring C.UTF-8: not a valid language tag\n[10:51:11] 'sass' errored after 1.57 s\n[10:51:11] Error in plugin 'gulp-uncss'\nMessage:\n    Fontconfig warning: ignoring C.UTF-8: not a valid language tag\n\nDetails:\n    domainEmitter: [object Object]\n    domain: [object Object]\n    domainThrown: false\n[10:51:11] 'build' errored after 2.43 s\nerror Command failed with exit code 1.", "stderr_lines": ["[10:51:05] Failed to load external module @babel/register", "Fontconfig warning: ignoring C.UTF-8: not a valid language tag", "[10:51:11] 'sass' errored after 1.57 s", "[10:51:11] Error in plugin 'gulp-uncss'", "Message:", "    Fontconfig warning: ignoring C.UTF-8: not a valid language tag", "", "Details:", "    domainEmitter: [object Object]", "    domain: [object Object]", "    domainThrown: false", "[10:51:11] 'build' errored after 2.43 s", "error Command failed with exit code 1."], "stdout": "yarn run v1.7.0\n$ gulp build --production\n[10:51:05] Requiring external module babel-register\n[10:51:08] Using gulpfile ~/vliegwel/src/api/email-templates/gulpfile.babel.js\n[10:51:08] Starting 'build'...\n[10:51:08] Starting 'clean'...\n[10:51:08] Finished 'clean' after 3.61 ms\n[10:51:08] Starting 'pages'...\n[10:51:09] Finished 'pages' after 851 ms\n[10:51:09] Starting 'sass'...\ninfo Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.", "stdout_lines": ["yarn run v1.7.0", "$ gulp build --production", "[10:51:05] Requiring external module babel-register", "[10:51:08] Using gulpfile ~/vliegwel/src/api/email-templates/gulpfile.babel.js", "[10:51:08] Starting 'build'...", "[10:51:08] Starting 'clean'...", "[10:51:08] Finished 'clean' after 3.61 ms", "[10:51:08] Starting 'pages'...", "[10:51:09] Finished 'pages' after 851 ms", "[10:51:09] Starting 'sass'...", "info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command."]}