Investigate influence of rxjs changes on application behaviour

[andreas-aeschlimann]

As discussed with @tobiasschweizer, there might be issues in Angular apps when the rxjs version is out of sync. We should find out how we could fix/bypass future issues.

[tobiasschweizer]

I have just run into a problem on my local machine:

Types of parameters 'source' and 'source' are incompatible.
Type 'Observable<ApiResponseError | ApiResponseData>' is not assignable to type 'Observable<ApiResponseData<ApiResponseError | LoginResponse>>'.
Types of property 'source' are incompatible.
Type 'import("...//...//knora-ui-ng-lib/node_modules/@knora/api/node_modules/rxjs/internal/Observable").Observable' is not assignable to type 'import("...//...//knora-ui-ng-lib/node_modules/rxjs/internal/Observable").Observable'.
Types of property 'operator' are incompatible.
Type 'import("...//...//knora-ui-ng-lib/node_modules/@knora/api/node_modules/rxjs/internal/Operator").Operator<any, any>' is not assignable to type 'import("...//...//knora-ui-ng-lib/node_modules/rxjs/internal/Operator").Operator<any, any>'.
Types of property 'call' are incompatible.
Type '(subscriber: import("...//...//knora-ui-ng-lib/node_modules/@knora/api/node_modules/rxjs/internal/Subscriber").Subscriber, source: any) => import("...//...//knora-ui-ng-lib/node_modules/@knora/api/node_modules/rxjs/internal/types").TeardownLogic' is not assignable to type '(subscriber: import("...//...//knora-ui-ng-lib/node_modules/rxjs/internal/Subscriber").Subscriber, source: any) => import("...//...//knora-ui-ng-lib/node_modules/rxjs/internal/types").TeardownLogic'.
Types of parameters 'subscriber' and 'subscriber' are incompatible.
Property '_parentOrParents' is missing in type 'import("...//...//knora-ui-ng-lib/node_modules/rxjs/internal/Subscriber").Subscriber' but required in type 'import("...//...//knora-ui-ng-lib/node_modules/@knora/api/node_modules/rxjs/internal/Subscriber").Subscriber'.

I think this is related to different versions of rxjs: knora-api-js-lib requires version 6.5.3 and Angular requires 6.4.0.

see ReactiveX/rxjs#3919

Requiring 6.4.0 in knora-api-js-lib resolved the issue.

[tobiasschweizer]

This post says (https://stackoverflow.com/questions/52141365/angular-6-rxjs-6-breaking-changes) the problem is not different versions but different copies of rxjs that were installed in parallel (which should not be the case).

[flavens]

I described the solution that fixed my errors in issue#148