add error handling (frontend) + exception changes

Co-authored-by: Christoph <tobi@urpost.de>
Co-authored-by: Mahgs <maxoerter@gmx.de>

src/main/resources/application-dev.properties

@@ -18,4 +18,5 @@ keycloak.verify-token-audience=true
 keycloak.use-resource-role-mappings=true
 
 keycloak.autodetect-bearer-only=true
-keycloak.confidential-port= 443
+keycloak.confidential-port=443
+server.error.include-stacktrace=always