diff --git a/src/js/src/app.ts b/src/js/src/app.ts
index 58eb40b..b7e709d 100644
--- a/src/js/src/app.ts
+++ b/src/js/src/app.ts
@@ -17,7 +17,10 @@ $SD.onConnected(() => {
       store.patchState({
         [StateKey.globalSettings]: settings,
       });
-      KimaiApi.config(settings.backendProviderConfig["kimai"]);
+      // Initial settings are undefined
+      if (settings?.backendProviderConfig?.["kimai"]) {
+        KimaiApi.config(settings.backendProviderConfig["kimai"]);
+      }
     }
   );
 });
diff --git a/src/js/src/lib/action/tracker-action.ts b/src/js/src/lib/action/tracker-action.ts
index 8cd55cf..e7b5b47 100644
--- a/src/js/src/lib/action/tracker-action.ts
+++ b/src/js/src/lib/action/tracker-action.ts
@@ -48,11 +48,9 @@ export function initTrackerAction(store: Store<AppState>) {
   });
 
   async function getApi() {
-    const {
-      backendProviderConfig: {
-        ["kimai"]: { url, user, token },
-      },
-    } = await store.once(StateKey.globalSettings);
-    return KimaiApi.config({ url, user, token }).get();
+    const globalSettings = await store.once(StateKey.globalSettings);
+    const apiConfig =
+      globalSettings?.backendProviderConfig?.["kimai"] ?? KimaiApi.emptyConfig;
+    return KimaiApi.config(apiConfig).get();
   }
 }
diff --git a/src/js/src/lib/api/kimai-api-tracker-connector.ts b/src/js/src/lib/api/kimai-api-tracker-connector.ts
index 49efe13..225309e 100644
--- a/src/js/src/lib/api/kimai-api-tracker-connector.ts
+++ b/src/js/src/lib/api/kimai-api-tracker-connector.ts
@@ -55,11 +55,19 @@ export class KimaiApiTrackerConnector implements ApiTrackerConnector {
   }
 
   async onRequestWorkedToday() {
-    this.#tracker.workedToday = await this.getWorkedToday({
-      projectId: this.settings(this.#tracker)!.projectId,
-      activityId: this.settings(this.#tracker)!.activityId,
-    });
-    this.#tracker.render();
+    const projectId = this.settings(this.#tracker)?.projectId;
+    const activityId = this.settings(this.#tracker)?.activityId;
+    if (projectId && activityId) {
+      try {
+        this.#tracker.workedToday = await this.getWorkedToday({
+          projectId,
+          activityId,
+        });
+        this.#tracker.render();
+      } catch (e) {
+        /* empty */
+      }
+    }
   }
 
   connect(tracker: Tracker) {
diff --git a/src/js/src/lib/api/kimai-api.ts b/src/js/src/lib/api/kimai-api.ts
index b83d4d7..1530b43 100644
--- a/src/js/src/lib/api/kimai-api.ts
+++ b/src/js/src/lib/api/kimai-api.ts
@@ -17,8 +17,14 @@ type ApiConfig = {
 export class KimaiApi {
   static instance: KimaiApi | null = null;
 
+  static emptyConfig = {
+    url: "",
+    user: "",
+    token: "",
+  };
+
   static config(c: ApiConfig) {
-    KimaiApi.get().config = c;
+    KimaiApi.get().config = c ?? KimaiApi.emptyConfig;
     return KimaiApi;
   }
 
@@ -62,10 +68,23 @@ export class KimaiApi {
     } as RequestInit; // eslint-disable-line
   }
 
+  assertValidConfig() {
+    if (!this.#user) {
+      throw new Error("Invalid config. User must not be empty.");
+    }
+    if (!this.#baseUrl) {
+      throw new Error("Invalid config. BaseUrl must not be empty.");
+    }
+    if (!this.#token) {
+      throw new Error("Invalid config. Token must not be empty.");
+    }
+  }
+
   async startTracking({
     projectId,
     activityId,
   }: KimaiBackendProviderPluginConfig): Promise<ApiResponse<TrackingItem>> {
+    this.assertValidConfig();
     const url = `${this.#baseUrl}api/timesheets`;
     const body = {
       begin: format(new Date(), "yyyy-MM-dd'T'HH:mm:ss"),
@@ -82,6 +101,7 @@ export class KimaiApi {
   }
 
   async stopTracking(id: number) {
+    this.assertValidConfig();
     const url = `${this.#baseUrl}api/timesheets/${id}/stop`;
     const options = {
       ...this.fetchOptions,
@@ -91,11 +111,13 @@ export class KimaiApi {
   }
 
   async getProjects() {
+    this.assertValidConfig();
     const url = `${this.#baseUrl}api/projects`;
     return tryFetch<Category[]>(url, this.fetchOptions);
   }
 
   async getActivities(projectId: number) {
+    this.assertValidConfig();
     const params = new URLSearchParams({
       project: String(projectId),
     });
@@ -107,6 +129,7 @@ export class KimaiApi {
     projectId: number,
     activityId: number
   ): Promise<ApiResponse<TimeEntry[]>> {
+    this.assertValidConfig();
     if (!projectId || !activityId) {
       return {
         success: false,