feat: correctly use error boundaries per-page

app/components/page-error.tsx

@@ -0,0 +1,43 @@
+import { RefreshCw, ServerOff } from "lucide-react";
+import { isRouteErrorResponse, useRevalidator } from "react-router";
+
+import { isConnectionError } from "~/server/headscale/api/error-client";
+import cn from "~/utils/cn";
+
+import Button from "./Button";
+import { ErrorBanner } from "./error-banner";
+
+interface PageErrorProps {
+  error: unknown;
+  page: string;
+}
+
+export default function PageError({ error, page }: PageErrorProps) {
+  const { revalidate, state } = useRevalidator();
+
+  if (isRouteErrorResponse(error) && isConnectionError(error.data)) {
+    return (
+      <div className="flex flex-col items-center justify-center py-24 text-center">
+        <ServerOff className={cn("h-12 w-12", "text-mist-400 dark:text-mist-500")} />
+        <h2 className="mt-4 text-lg font-semibold">{page} Unavailable</h2>
+        <p className="mt-1 max-w-sm text-sm text-mist-500 dark:text-mist-400">
+          This page could not be loaded because the Headscale server is unreachable. It will be
+          available once the connection is restored.
+        </p>
+        <Button
+          className="mt-6"
+          variant="light"
+          onPress={() => revalidate()}
+          isDisabled={state === "loading"}
+        >
+          <RefreshCw
+            className={cn("mr-2 inline-block h-4 w-4", state === "loading" && "animate-spin")}
+          />
+          Retry
+        </Button>
+      </div>
+    );
+  }
+
+  return <ErrorBanner className="max-w-2xl" error={error} />;
+}