Better lightning address error handling (#2089)

Author: ekzyis

lib/lnurl.js

@@ -3,6 +3,7 @@ import { bech32 } from 'bech32'
 import { lnAddrSchema } from './validate'
 import { FetchTimeoutError } from '@/lib/fetch'
 import { WALLET_CREATE_INVOICE_TIMEOUT_MS } from './constants'
+import { assertContentTypeJson, assertResponseOk, ResponseAssertError } from '@/lib/url'
 
 export function encodeLNUrl (url) {
   const words = bech32.toWords(Buffer.from(url.toString(), 'utf8'))
@@ -35,25 +36,33 @@ export async function lnAddrOptions (addr, { signal } = {}) {
     // support HTTP and HTTPS during development
     protocol = process.env.NEXT_PUBLIC_URL.split('://')[0]
   }
-  const unexpectedErrorMessage = `An unexpected error occurred fetching the Lightning Address metadata for ${addr}. Check the address and try again.`
-  let res
+
+  const unexpectedErrorMessage = 'Lightning address validation failed. Make sure you entered the correct address.'
+  let body
   const url = `${protocol}://${domain}/.well-known/lnurlp/${name}`
   try {
-    const req = await fetch(url, { signal })
-    res = await req.json()
+    const res = await fetch(url, { signal })
+    assertResponseOk(res)
+    assertContentTypeJson(res)
+    body = await res.json()
   } catch (err) {
-    console.log('Error fetching lnurlp', err)
+    console.log('Error fetching lnurlp:', err)
+    if (err instanceof ResponseAssertError) {
+      throw err
+    }
     if (err.name === 'TimeoutError') {
       throw new FetchTimeoutError('GET', url, WALLET_CREATE_INVOICE_TIMEOUT_MS)
     }
-    // If `fetch` fails, or if `req.json` fails, catch it here and surface a reasonable error
+    if (err.name === 'SyntaxError') {
+      throw new Error(`GET ${url}: invalid JSON`)
+    }
     throw new Error(unexpectedErrorMessage)
   }
-  if (res.status === 'ERROR') {
+  if (body.status === 'ERROR') {
     // if the response doesn't adhere to spec by providing a `reason` entry, returns a default error message
-    throw new Error(res.reason ?? unexpectedErrorMessage)
+    throw new Error(body.reason ?? unexpectedErrorMessage)
   }
 
-  const { minSendable, maxSendable, ...leftOver } = res
+  const { minSendable, maxSendable, ...leftOver } = body
   return { min: minSendable / 1000, max: maxSendable / 1000, ...leftOver }
 }

lib/url.js

@@ -213,7 +213,7 @@ export function parseNwcUrl (walletConnectUrl) {
   return params
 }
 
-class ResponseAssertError extends Error {
+export class ResponseAssertError extends Error {
   constructor (res, { method } = {}) {
     if (method) {
       super(`${method} ${res.url}: ${res.status} ${res.statusText}`)