Show alias errors when creating an identity

The errors weren't reactive state, so the hints never rendered.

src/views/auth/CreateIdentity.svelte

@@ -16,10 +16,10 @@
   let notMatchingPassphrases = $state<boolean>();
   let passphraseRepeat = $state("");
   let alias = $state("");
-  const errors: { alias: ErrorWrapper[]; passphrase: ErrorWrapper[] } = {
+  const errors = $state<{ alias: ErrorWrapper[]; passphrase: ErrorWrapper[] }>({
     alias: [],
     passphrase: [],
-  };
+  });
 
   const validatePassphraseRepeat = debounce(() => {
     if (passphrase !== passphraseRepeat && passphraseRepeat.length !== 0) {

tests/e2e/createIdentity.spec.ts

@@ -0,0 +1,33 @@
+import { expect, test } from "@tests/support/fixtures.js";
+
+test("explains why an alias is invalid", async ({ page }) => {
+  await page.route(
+    url => url.pathname === "/startup",
+    route =>
+      route.fulfill({
+        status: 500,
+        json: {
+          code: "IdentityError.MissingProfile",
+          message: "No profile found",
+        },
+      }),
+  );
+  await page.goto("/");
+
+  const alias = page.getByPlaceholder("Enter desired alias");
+  await alias.fill("has space");
+  await expect(
+    page.getByText("Alias cannot contain whitespace."),
+  ).toBeVisible();
+
+  await alias.fill("a".repeat(33));
+  await expect(
+    page.getByText("Alias is too long, max 32 characters."),
+  ).toBeVisible();
+  await expect(page.getByText("Alias cannot contain whitespace.")).toBeHidden();
+
+  await alias.fill("alice");
+  await expect(
+    page.getByText("Max 32 characters, no whitespace."),
+  ).toBeVisible();
+});