Avoid intermediate Observable for getOne() #7739

Similar to 2c2c875 but for getOne().
And for the same reason too. We must be able to catch error in our apps
if needed, so we must avoid intermediate observable that do not properly
forward errors.

With this fix we finally restore the historical behavior of redirecting to
an error page when our app resolve an non-existing object.

Most likely, we should to the same for getAll/watchAll some day.

projects/natural/src/lib/services/abstract-model.service.ts

@@ -1,12 +1,12 @@
 import {Apollo, gql} from 'apollo-angular';
-import {NetworkStatus, WatchQueryFetchPolicy, FetchResult} from '@apollo/client/core';
+import {FetchResult, NetworkStatus, WatchQueryFetchPolicy} from '@apollo/client/core';
 import {AbstractControl, AsyncValidatorFn, FormControl, FormGroup, ValidatorFn} from '@angular/forms';
 
 import {DocumentNode} from 'graphql';
 
 import {debounce, defaults, merge, mergeWith, omit, pick} from 'lodash-es';
-import {Observable, of, OperatorFunction, ReplaySubject, Subject, Subscription} from 'rxjs';
-import {debounceTime, filter, first, map, shareReplay, switchMap, takeUntil} from 'rxjs/operators';
+import {Observable, of, OperatorFunction, ReplaySubject, Subscription} from 'rxjs';
+import {debounceTime, filter, first, map, shareReplay, switchMap, takeUntil, takeWhile} from 'rxjs/operators';
 import {NaturalQueryVariablesManager} from '../classes/query-variable-manager';
 import {Literal} from '../types/types';
 import {makePlural, mergeOverrideArray, relationsToIds, upperCaseFirstLetter} from '../classes/utility';
@@ -169,25 +169,18 @@ export abstract class NaturalAbstractModelService<
         this.throwIfObservable(id);
         this.throwIfNotQuery(this.oneQuery);
 
-        const resultObservable = new Subject<Tone>();
-
         const queryRef = this.apollo.watchQuery<Tone, Vone>({
             query: this.oneQuery,
             variables: this.getVariablesForOne(id),
             fetchPolicy: 'cache-and-network',
             nextFetchPolicy: 'cache-only',
         });
 
-        const subscription = queryRef.valueChanges.pipe(filter(r => !!r.data)).subscribe(result => {
-            const data = (result.data as Literal)[this.name];
-            resultObservable.next(data);
-            if (result.networkStatus === NetworkStatus.ready) {
-                resultObservable.complete();
-                subscription.unsubscribe();
-            }
-        });
-
-        return resultObservable;
+        return queryRef.valueChanges.pipe(
+            filter(result => !!result.data),
+            takeWhile(result => result.networkStatus !== NetworkStatus.ready, true),
+            map(result => (result.data as Literal)[this.name]),
+        );
     }
 
     /**