Show email registration errors in UI

- Add error field to EmailNotificationState type
- Set user-friendly error messages in MailNotifications.register() for:
  missing signer, missing server config, NIP-98 auth failure,
  network errors, and server errors
- Clear error on successful registration
- Show inline error banner in the email settings card
- Return early on registration failure (like push does)
- Clear error when user edits email/frequency or clicks reset

src/app/mail/index.ts

@@ -16,21 +16,46 @@ export class MailNotifications {
     const $pubkey = User.require($app).pubkey
     const $signer = $app.signer
 
-    if (!$signer) throw new Error("No signer available")
+    if (!$signer) {
+      emailNotificationState.set({error: "No signer available. Check your browser extension."})
+      throw new Error("No signer available")
+    }
+
+    if (!EMAIL_NOTIFICATION_SERVER) {
+      emailNotificationState.set({error: "Email notification server is not configured."})
+      throw new Error("Email notification server not configured")
+    }
+
+    let authEvent
+    try {
+      authEvent = await $signer.sign(await makeHttpAuth(EMAIL_NOTIFICATION_SERVER, "POST"))
+    } catch (e) {
+      emailNotificationState.set({error: "Failed to create authentication. Check your signer."})
+      throw new Error("Failed to sign NIP-98 auth")
+    }
 
-    const authEvent = await $signer.sign(await makeHttpAuth(EMAIL_NOTIFICATION_SERVER, "POST"))
     const authHeader = makeHttpAuthHeader(authEvent)
 
-    const res = await fetch(buildUrl(EMAIL_NOTIFICATION_SERVER, "subscription", "email"), {
-      method: "POST",
-      body: JSON.stringify({email, frequency, pubkey: $pubkey}),
-      headers: {Authorization: authHeader, "Content-Type": "application/json"},
-    })
+    let res
+    try {
+      res = await fetch(buildUrl(EMAIL_NOTIFICATION_SERVER, "subscription", "email"), {
+        method: "POST",
+        body: JSON.stringify({email, frequency, pubkey: $pubkey}),
+        headers: {Authorization: authHeader, "Content-Type": "application/json"},
+      })
+    } catch (e) {
+      emailNotificationState.set({error: `Could not reach email server. Check your connection.`})
+      throw new Error("Network error")
+    }
 
-    if (!res.ok) throw new Error(`Registration failed: ${await res.text()}`)
+    if (!res.ok) {
+      const text = await res.text().catch(() => "unknown error")
+      emailNotificationState.set({error: `Registration failed: ${text}`})
+      throw new Error(`Registration failed: ${text}`)
+    }
 
     const {key, callback} = await res.json()
-    emailNotificationState.set({key, callback, email, frequency})
+    emailNotificationState.set({key, callback, email, frequency, error: undefined})
   }
 
   async unregister() {

src/app/push/adapters/common.ts

@@ -45,6 +45,7 @@ export type EmailNotificationState = {
   callback?: string
   email?: string
   frequency?: string
+  error?: string
 }
 
 export const emailNotificationState = withGetter(writable<EmailNotificationState>({}))

src/routes/settings/alerts/+page.svelte

@@ -16,9 +16,17 @@
   import {Push} from "@app/push"
   import {Mail} from "@app/mail"
   import {notificationSettings} from "@app/settings"
+  import {emailNotificationState} from "@app/push/adapters/common"
+
+  const clearError = () => {
+    if ($emailNotificationState.error) {
+      emailNotificationState.set({...emailNotificationState.get(), error: undefined})
+    }
+  }
 
   const reset = () => {
     settings = {...notificationSettings.get()}
+    clearError()
   }
 
   const onsubmit = preventDefault(async () => {
@@ -52,8 +60,13 @@
           await Mail.register(settings.emailAddress, settings.emailFrequency)
           await Mail.enable()
         } catch (e) {
-          console.warn("Failed to enable email notifications:", e)
-          pushToast({theme: "error", message: "Failed to enable email notifications."})
+          settings.email = false
+          await sleep(300)
+          return pushToast({
+            theme: "error",
+            message: `Failed to enable email notifications.`,
+            action: {message: "Details", onclick: () => emailNotificationState.set({...emailNotificationState.get(), error: undefined})},
+          })
         }
       } else if (!settings.email) {
         await Mail.disable()
@@ -161,6 +174,7 @@
               type="email"
               class="input input-bordered w-full"
               bind:value={settings.emailAddress}
+              oninput={clearError}
               placeholder="you@example.com" />
           {/snippet}
         </FieldInline>
@@ -169,13 +183,18 @@
             <p>Frequency</p>
           {/snippet}
           {#snippet input()}
-            <select class="select select-bordered" bind:value={settings.emailFrequency}>
+            <select class="select select-bordered" bind:value={settings.emailFrequency} onchange={clearError}>
               <option value="daily">Daily</option>
               <option value="weekly">Weekly</option>
             </select>
           {/snippet}
         </FieldInline>
       {/if}
+      {#if $emailNotificationState.error}
+        <div class="text-sm text-red-500 bg-red-50 rounded-lg p-3">
+          {$emailNotificationState.error}
+        </div>
+      {/if}
     </div>
     <div class="card sticky -bottom-3 shadow-md flex flex-row items-center justify-between gap-4">
       <Button class="button button-neutral" onclick={reset} disabled={loading}