Translate dashboard panel url error message

src/panels/config/lovelace/dashboards/dialog-lovelace-dashboard-detail.ts

@@ -283,6 +283,15 @@ export class DialogLovelaceDashboardDetail extends LitElement {
       }
       this.closeDialog();
     } catch (err: any) {
+      if (err?.translation_key === "url_already_exists") {
+        this._error = {
+          url_path: this.hass!.localize(
+            "ui.panel.config.lovelace.dashboards.detail.url_already_exists",
+            err?.translation_placeholders
+          ),
+        };
+        return;
+      }
       this._error = { base: err?.message || "Unknown error" };
     } finally {
       this._submitting = false;

src/translations/en.json

@@ -3433,6 +3433,7 @@
               "title": "Title",
               "title_required": "Title is required.",
               "url": "URL",
+              "url_already_exists": "The {url} URL is already in use. Please choose a different one.",
               "url_error_msg": "The URL should contain a - and cannot contain spaces or special characters, except for _ and -",
               "require_admin": "Admin only",
               "delete": "Delete",