feat: add themed Error page

src/login/KcPage.tsx

@@ -13,10 +13,13 @@ const Login = lazy(() => import("./pages/Login"));
 const Register = lazy(() => import("./pages/Register"));
 const LoginUpdateProfile = lazy(() => import("./pages/LoginUpdateProfile"));
 const LoginUpdatePassword = lazy(() => import("./pages/LoginUpdatePassword"));
+
+const Error = lazy(() => import("./pages/Error"));
 const LoginResetPassword = lazy(() => import("./pages/LoginResetPassword"));
 const LoginPageExpired = lazy(() => import("./pages/LoginPageExpired"));
 const LoginVerifyEmail = lazy(() => import("./pages/LoginVerifyEmail"));
 
+
 const doMakeUserConfirmPassword = false;
 
 export default function KcPage(props: { kcContext: KcContext }) {
@@ -80,6 +83,14 @@ export default function KcPage(props: { kcContext: KcContext }) {
                                 doUseDefaultCss={false}
                             />
                         );
+                    case "error.ftl":
+                        return (
+                            <Error
+                                {...{ kcContext, i18n, classes }}
+                                Template={Template}
+                                doUseDefaultCss={false}
+                            />
+                          );
                     case "login-reset-password.ftl":
                         return (
                             <LoginResetPassword

src/login/pages/Error.stories.tsx

@@ -0,0 +1,64 @@
+import type { Meta, StoryObj } from "@storybook/react";
+import { createKcPageStory } from "../KcPageStory";
+
+const { KcPageStory } = createKcPageStory({ pageId: "error.ftl" });
+
+const meta = {
+    title: "login/error.ftl",
+    component: KcPageStory
+} satisfies Meta<typeof KcPageStory>;
+
+export default meta;
+
+type Story = StoryObj<typeof meta>;
+
+export const Default: Story = {
+    render: () => (
+        <KcPageStory
+            kcContext={{
+                message: {
+                    summary: "An unexpected error occurred. Please try again."
+                }
+            }}
+        />
+    )
+};
+
+/**
+ * AccountLocked:
+ * - Purpose: Tests the error page for account lockout scenarios.
+ * - Scenario: Simulates a user whose account has been locked due to too many failed login attempts.
+ * - Key Aspect: Displays a specific error message about account lockout.
+ */
+export const AccountLocked: Story = {
+    render: () => (
+        <KcPageStory
+            kcContext={{
+                message: {
+                    summary: "Your account has been temporarily locked due to too many failed login attempts."
+                }
+            }}
+        />
+    )
+};
+
+/**
+ * WithClientBaseUrl:
+ * - Purpose: Tests the error page when a client base URL is available.
+ * - Scenario: Simulates an error with the option to return to the application.
+ * - Key Aspect: Displays a "Back to Application" button in addition to "Back to Login".
+ */
+export const WithClientBaseUrl: Story = {
+    render: () => (
+        <KcPageStory
+            kcContext={{
+                message: {
+                    summary: "Session expired. Please log in again."
+                },
+                client: {
+                    baseUrl: "https://hubee.com"
+                }
+            }}
+        />
+    )
+};

src/login/pages/Error.tsx

@@ -0,0 +1,49 @@
+import { getKcClsx } from "keycloakify/login/lib/kcClsx";
+import type { PageProps } from "keycloakify/login/pages/PageProps";
+import type { KcContext } from "../KcContext";
+import type { I18n } from "../i18n";
+import Alert from "@codegouvfr/react-dsfr/Alert";
+import { fr } from "@codegouvfr/react-dsfr";
+
+export default function Error(props: PageProps<Extract<KcContext, { pageId: "error.ftl" }>, I18n>) {
+    const { kcContext, i18n, doUseDefaultCss, Template, classes } = props;
+
+    const { kcClsx } = getKcClsx({
+        doUseDefaultCss,
+        classes
+    });
+
+    const { url, message, client } = kcContext;
+
+    const { msg } = i18n;
+
+    return (
+        <Template
+            kcContext={kcContext}
+            i18n={i18n}
+            doUseDefaultCss={doUseDefaultCss}
+            classes={classes}
+            displayMessage={false}
+            headerNode={msg("errorTitle")}
+        >
+            <Alert
+                severity="error"
+                description={message?.summary}
+                className={fr.cx("fr-mb-4w")}
+                small
+            />
+
+            <div className={kcClsx("kcFormGroupClass")} style={{ display: "flex", justifyContent: "flex-end" }}>
+                {client.baseUrl !== undefined ? (
+                    <a className={fr.cx("fr-link")} href={client.baseUrl}>
+                        {msg("backToApplication")}
+                    </a>
+                ) : (
+                    <a className={fr.cx("fr-link")} href={url.loginUrl}>
+                        {msg("backToLogin")}
+                    </a>
+                )}
+            </div>
+        </Template>
+    );
+}