fix: avoid to send to backend null access or refresh token

https://issues.unige.ch/browse/AOU-1139

projects/solidify-frontend/src/lib/auth/oauth2.service.ts

@@ -26,6 +26,7 @@ import {
 import {DefaultSolidifyEnvironment} from "../environments/environment.solidify-defaults";
 import {ENVIRONMENT} from "../injection-tokens";
 import {AbstractBaseService} from "../services/abstract-base.service";
+import {isNullOrUndefinedOrWhiteString} from "../tools";
 import {
   OAuthErrorEvent,
   OAuthEvent,
@@ -92,9 +93,14 @@ export class OAuth2Service extends AbstractBaseService {
    * there is no refresh_token in this flow.
    */
   public refreshToken(): Observable<boolean> {
+    const refreshToken = this._storage.getItem("refresh_token");
+    if (isNullOrUndefinedOrWhiteString(refreshToken)) {
+      this.eventsSubject.next(new OAuthErrorEvent("token_refresh_error", new Error("Refresh token is not defined")));
+      return of(false);
+    }
     let params = new HttpParams()
       .set("grant_type", "refresh_token")
-      .set("refresh_token", this._storage.getItem("refresh_token"))
+      .set("refresh_token", refreshToken)
       .set("scope", this.environment.scope);
     if (this.environment.dummyClientSecret) {
       params = params.set("client_secret", this.environment.dummyClientSecret);