server request depends on the OpenAPI.Base is set. Make sure it happens before connecting to the server

src/Umbraco.Web.UI.Client/src/apps/app/app.element.ts

@@ -74,7 +74,6 @@ export class UmbAppElement extends UmbLitElement {
 
 	async #setup() {
 		if (this.serverUrl === undefined) throw new Error('No serverUrl provided');
-		OpenAPI.BASE = this.serverUrl;
 		const redirectUrl = `${window.location.origin}${this.backofficePath}`;
 
 		this.#serverConnection = new UmbServerConnection(this.serverUrl);

src/Umbraco.Web.UI.Client/src/apps/app/server-connection.ts

@@ -1,4 +1,4 @@
-import { RuntimeLevelModel, ServerResource } from '@umbraco-cms/backoffice/backend-api';
+import { OpenAPI, RuntimeLevelModel, ServerResource } from '@umbraco-cms/backoffice/backend-api';
 import { UmbBooleanState } from '@umbraco-cms/backoffice/observable-api';
 import { tryExecute } from '@umbraco-cms/backoffice/resources';
 
@@ -11,6 +11,7 @@ export class UmbServerConnection {
 
 	constructor(serverUrl: string) {
 		this.#url = serverUrl;
+		OpenAPI.BASE = this.#url;
 	}
 
 	/**