Angular 6 Unit Tests: An error was thrown in afterAll\nReferenceError: Can't find variable: $...

When running my unit tests, from time to time, even if they pass, at the end of all the tests running, I will get the following error.

On my Jenkins CI build running PhantomJS:

.PhantomJS 2.1.1 (Linux 0.0.0) ERROR
{
"message": "An error was thrown in afterAll\nReferenceError: Can't find variable: $ thrown",
"str": "An error was thrown in afterAll\nReferenceError: Can't find variable: $ thrown"
}


Or on Chrome:

Chrome 67.0.3396 (Windows 7 0.0.0) ERROR
{
"message": "An error was thrown in afterAll\n[object ErrorEvent] thrown",
"str": "An error was thrown in afterAll\n[object ErrorEvent] thrown"
}


I also have really unreliable tests, without changing anything some times they would succeed and other times the same tests would fail, so I knew something weird was going on.

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