ng test error with PhantomJS , getting less error

error :-npm run coverage

> gd@2.0.0 coverage
> ng test --code-coverage --reporters=coverage

⠙ Generating browser application bundles (phase: building)...19 01 2022 01:29:08.151:INFO [karma-server]: Karma v6.3.11 server started at http://localhost:9876/
19 01 2022 01:29:08.158:INFO [launcher]: Launching browsers PhantomJS with concurrency unlimited
19 01 2022 01:29:08.183:INFO [launcher]: Starting browser PhantomJS
✔ Browser application bundle generation complete.

./src/styles.less - Error: Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):
ModuleBuildError: Module build failed (from ./node_modules/@angular-devkit/build-angular/node_modules/less-loader/dist/cjs.js):

Chunk.split is not a function

at processResult (C:\Users\bdadwhal-etc\angular-migration8.1\node_modules\webpack\lib\NormalModule.js:713:19)
at C:\Users\bdadwhal-etc\angular-migration8.1\node_modules\webpack\lib\NormalModule.js:819:5
at C:\Users\bdadwhal-etc\angular-migration8.1\node_modules\loader-runner\lib\LoaderRunner.js:399:11
at C:\Users\bdadwhal-etc\angular-migration8.1\node_modules\loader-runner\lib\LoaderRunner.js:251:18
at context.callback (C:\Users\bdadwhal-etc\angular-migration8.1\node_modules\loader-runner\lib\LoaderRunner.js:124:13)
at Object.lessLoader (C:\Users\bdadwhal-etc\angular-migration8.1\node_modules\@angular-devkit\build-angular\node_modules\less-loader\dist\index.js:54:5)

Error: src/app/citation/citation-list/citation-list.component.spec.ts:433:76 - error TS2345: Argument of type 'Observable<{}>' is not assignable to parameter of type 'void'.

433 spyOn(component['detailsService'], 'bibDetailsAction').and.returnValue(Observable.of({}));
~~~~~~~~~~~~~~~~~

Error: src/app/citation/store/details.service.spec.ts:59:81 - error TS2345: Argument of type 'Observable<{ bibDetails: { title: string; publishedDate: string; inventors: string[]; applicants: string[]; application: { country: string; display: string; date: string; type: string; kind: string; id: string; docKey: string; }; abstract: string; priority: any[]; }; classifications: { ...; }; }>' is not assignable to parameter of type 'Observable'.
Type '{ bibDetails: { title: string; publishedDate: string; inventors: string[]; applicants: string[]; application: { country: string; display: string; date: string; type: string; kind: string; id: string; docKey: string; }; abstract: string; priority: any[]; }; classifications: { ...; }; }' is missing the following properties from type 'BibResponse': docNumber, toDocNumber, toBibDetails, toClassifications

59 spyOn(service['citationStoreService'], 'getCitationDetail').and.returnValue(Observable.of(details));
~~~~~~~~~~~~~~~~~~~~~~

Error: src/app/page-content/events/controller.event.spec.ts:35:68 - error TS2345: Argument of type 'Observable' is not assignable to parameter of type 'Observable'.
Type 'DocNumber' is missing the following properties from type 'LookupResponse': group, title, query

35 spyOn(service['lookupEvent'], 'getObservable').and.returnValue(Observable.of(new DocNumber()));
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Error: src/app/page-content/events/lookup.event.spec.ts:78:82 - error TS2345: Argument of type '{ status: number; }' is not assignable to parameter of type 'Expected'.
Type '{ status: number; }' is missing the following properties from type '{ readonly name: ExpectedRecursive<"HttpErrorResponse">; readonly message: ExpectedRecursive; readonly error:
any; readonly ok: ExpectedRecursive; ... 4 more ...; readonly type: ExpectedRecursive<...>; }': name, message, error, ok, and 4 more.

78 expect(service['applicationErrorEvent']['lookupError']).toHaveBeenCalledWith(httpError);
~~~~~~~~~

./node_modules/css-loader/dist/cjs.js??ruleSet[1].rules[7].rules[0].oneOf[1].use[1]!./node_modules/postcss-loader/dist/cjs.js??ruleSet[1].rules[7].rules[0].oneOf[1].use[2]!./node_modules/@angular-devkit/build-angular/node_modules/less-loader/dist/cjs.js??ruleSet[1].rules[7].rules[1].use[0]!./src/styles.less - Error: Module build failed (from ./node_modules/@angular-devkit/build-angular/node_modules/less-loader/dist/cjs.js):

Chunk.split is not a function

Reproduce the failure with npm run coverage and separate the styles.less build error from the TypeScript test errors. Read the reported specs—citation-list.component.spec.ts, details.service.spec.ts, controller.event.spec.ts, and lookup.event.spec.ts—then verify that the coverage command completes without these errors.

Written by the indexing model from the issue text.