ERROR: 'ERROR', TypeError - while running `ng test` with angular 6 project - PhantomJS

When I run ng test, it runs the tests both in chrome and PhantomJS and here is the output:

PhantomJS 2.1.1 (Linux 0.0.0): Executed 37 of 37 (1 FAILED) (0 secs / 15.752 secs)
Chrome 68.0.3440 (Linux 0.0.0): Executed 36 of 37 SUCCESS (0 secs / 10.731 secs)
PhantomJS 2.1.1 (Linux 0.0.0) ERROR: 'ERROR', TypeError{line: 1364, sourceURL: 'http://localhost:9876/_karma_webpack_/vendor.js', stack: '_matches@http://localhost:9876/_karma_webpack_/vendor.js:1364:73
matchesElement@http://localhost:9876/_karma_webpack_/vendor.js:5450:30
processLeaveNode@http://localhost:9876/_karma_webpack_/vendor.js:4246:39
http://localhost:9876/_karma_webpack_/vendor.js:4370:78
forEach@[native code]
http://localhost:9876/_karma_webpack_/vendor.js:4370:34
flush@http://localhost:9876/_karma_webpack_/vendor.js:4275:34
flush@http://localhost:9876/_karma_webpack_/vendor.js:5119:37
http://localhost:9876/_karma_webpack_/vendor.js:115207:35
invoke@http://localhost:9876/_karma_webpack_/vendor.js:145347:31
onInvoke@http://localhost:9876/_karma_webpack_/vendor.js:143657:45
invoke@http://localhost:9876/_karma_webpack_/vendor.js:145346:40
run@http://localhost:9876/_karma_webpack_/vendor.js:145097:49
runOutsideAngular@http://localhost:9876/_karma_webpack_/vendor.js:58319:31
end@http://localhost:9876/_karma_webpack_/vendor.js:115205:41
end@http://localhost:9876/_karma_webpack_/vendor.js:65776:30
detectChanges@http://localhost:9876/_karma_webpack_/vendor.js:63244:23
http://localhost:9876/_karma_webpack_/vendor.js:59117:76
forEach@[native code]
tick@http://localhost:9876/_karma_webpack_/vendor.js:59117:32
http://localhost:9876/_karma_webpack_/vendor.js:59009:109
invoke@http://localhost:9876/_karma_webpack_/vendor.js:145347:31
onInvoke@http://localhost:9876/_karma_webpack_/vendor.js:143657:45
invoke@http://localhost:9876/_karma_webpack_/vendor.js:145346:40
onInvoke@http://localhost:9876/_karma_webpack_/vendor.js:58360:39
invoke@http://localhost:9876/_karma_webpack_/vendor.js:145346:40
run@http://localhost:9876/_karma_webpack_/vendor.js:145097:49
run@http://localhost:9876/_karma_webpack_/vendor.js:58274:31
next@http://localhost:9876/_karma_webpack_/vendor.js:59009:84
http://localhost:9876/_karma_webpack_/vendor.js:58091:56
__tryOrUnsub@http://localhost:9876/_karma_webpack_/vendor.js:131365:20
next@http://localhost:9876/_karma_webpack_/vendor.js:131303:34
_next@http://localhost:9876/_karma_webpack_/vendor.js:131247:30
next@http://localhost:9876/_karma_webpack_/vendor.js:131224:23
next@http://localhost:9876/_karma_webpack_/vendor.js:130990:29
emit@http://localhost:9876/_karma_webpack_/vendor.js:58083:80
checkStable@http://localhost:9876/_karma_webpack_/vendor.js:58329:39
onLeave@http://localhost:9876/_karma_webpack_/vendor.js:58396:16
onInvokeTask@http://localhost:9876/_karma_webpack_/vendor.js:58354:24
invokeTask@http://localhost:9876/_karma_webpack_/vendor.js:145379:48
runTask@http://localhost:9876/_karma_webpack_/vendor.js:145147:57
invokeTask@http://localhost:9876/_karma_webpack_/vendor.js:145455:41
PhantomJS 2.1.1 (Linux 0.0.0): Executed 37 of 37 (1 FAILED) (15.454 secs / 15.752 secs)
Chrome 68.0.3440 (Linux 0.0.0): Executed 37 of 37 SUCCESS (11.067 secs / 10.941 secs)
TOTAL: 1 FAILED, 73 SUCCESS
TOTAL: 1 FAILED, 73 SUCCESS
TOTAL: 1 FAILED, 73 SUCCESS

There is nothing in here about any of the possible tests that fail, so what is generating this error? My project has been acting up recently by not recognizing keywords like Date, or the fact that it wouldn't let me use .length property on a list. I ran npm install after that and those "precompiler" errors went away, but not this is happening.

Also, there were 74 tests that ran (37 in Chrome, 37 in PhantomJS) and 73 passed. So is there an issue with one of the browsers?