diff --git a/src/handlers/auth.js b/src/handlers/auth.js
index 02b00d3..2e2796f 100644
--- a/src/handlers/auth.js
+++ b/src/handlers/auth.js
@@ -36,13 +36,13 @@ const getRoute = (endpoint) => {
 /**
  * @param {object} [request]
  * @param {string} [endpoint]
- * @param {{onError?: () => void; config: {audience?: string | string[], clientId?: string, clientSecret?: string, issuerURL?: string, siteUrl?: string, postLoginRedirectUrl?: string, postLogoutRedirectUrl?: string}}} options
+ * @param {{onError?: () => void; config: {audience?: string | string[], clientId?: string, clientSecret?: string, issuerURL?: string, siteUrl?: string, postLoginRedirectUrl?: string, postLogoutRedirectUrl?: string}}} [options]
  * @returns {(req, res) => any}
  */
 export default (request, endpoint, options) => {
-  if (!config.clientOptions.authDomain && !options?.config?.issuerURL)
+  if (!config.clientOptions.authDomain)
     throw new Error(
-      "env variable 'KINDE_ISSUER_URL' is not set and not passed in options"
+      "The environment variable 'KINDE_ISSUER_URL' is required. Set it in your .env file"
     );
 
   if (!config.clientOptions.clientId && !options?.config?.clientId)
diff --git a/src/routerClients/AppRouterClient.js b/src/routerClients/AppRouterClient.js
index 275223a..b59f083 100644
--- a/src/routerClients/AppRouterClient.js
+++ b/src/routerClients/AppRouterClient.js
@@ -25,9 +25,9 @@ export default class AppRouterClient extends RouterClient {
       logoutRedirectURL:
         options?.config?.postLogoutRedirectUrl ||
         config.clientOptions.logoutRedirectURL,
-      redirectURL:
-        `${options?.config?.siteUrl}/api/auth/kinde_callback` ||
-        config.clientOptions.redirectURL,
+      redirectURL: options?.config?.siteUrl
+        ? `${options?.config?.siteUrl}/api/auth/kinde_callback`
+        : config.clientOptions.redirectURL,
       siteUrl: config.redirectURL || options.config.siteUrl
     };
     this.kindeClient = createKindeServerClient(
diff --git a/src/routerClients/PagesRouterClient.js b/src/routerClients/PagesRouterClient.js
index a82139c..f519eeb 100644
--- a/src/routerClients/PagesRouterClient.js
+++ b/src/routerClients/PagesRouterClient.js
@@ -25,9 +25,9 @@ export default class PagesRouterClient extends RouterClient {
       logoutRedirectURL:
         options?.config?.postLogoutRedirectUrl ||
         config.clientOptions.logoutRedirectURL,
-      redirectURL:
-        `${options?.config?.siteUrl}/api/auth/kinde_callback` ||
-        config.clientOptions.redirectURL,
+      redirectURL: options?.config?.siteUrl
+        ? `${options?.config?.siteUrl}/api/auth/kinde_callback`
+        : config.clientOptions.redirectURL,
       siteUrl: config.redirectURL || options.config.siteUrl
     };
     this.kindeClient = createKindeServerClient(