Return some error codes when adding peers

Partly addresses #925. Not finished.

src/lib/error-with-code.js

@@ -0,0 +1,20 @@
+/**
+ * Create an `Error` with a `code` property.
+ *
+ * @example
+ * const err = new ErrorWithCode('INVALID_DATA', 'data was invalid')
+ * err.message
+ * // => 'data was invalid'
+ * err.code
+ * // => 'INVALID_DATA'
+ */
+export class ErrorWithCode extends Error {
+  /**
+   * @param {string} code
+   * @param {string} message
+   */
+  constructor(code, message) {
+    super(message)
+    /** @readonly */ this.code = code
+  }
+}

src/member-api.js

@@ -16,6 +16,7 @@ import { keyBy } from './lib/key-by.js'
 import { abortSignalAny } from './lib/ponyfills.js'
 import timingSafeEqual from './lib/timing-safe-equal.js'
 import { isHostnameIpAddress } from './lib/is-hostname-ip-address.js'
+import { ErrorWithCode } from './lib/error-with-code.js'
 import { MEMBER_ROLE_ID, ROLES, isRoleIdForNewInvite } from './roles.js'
 import { wsCoreReplicator } from './server/ws-core-replicator.js'
 /**
@@ -273,10 +274,11 @@ export class MemberApi extends TypedEmitter {
     baseUrl,
     { dangerouslyAllowInsecureConnections = false } = {}
   ) {
-    assert(
-      isValidServerBaseUrl(baseUrl, { dangerouslyAllowInsecureConnections }),
-      'Base URL is invalid'
-    )
+    if (
+      !isValidServerBaseUrl(baseUrl, { dangerouslyAllowInsecureConnections })
+    ) {
+      throw new ErrorWithCode('INVALID_URL', 'Server base URL is invalid')
+    }
 
     const { serverDeviceId } = await this.#addServerToProject(baseUrl)
 
@@ -319,13 +321,15 @@ export class MemberApi extends TypedEmitter {
         err && typeof err === 'object' && 'message' in err
           ? err.message
           : String(err)
-      throw new Error(
+      throw new ErrorWithCode(
+        'NETWORK_ERROR',
         `Failed to add server peer due to network error: ${message}`
       )
     }
 
     if (response.status !== 200 && response.status !== 201) {
-      throw new Error(
+      throw new ErrorWithCode(
+        'INVALID_SERVER_RESPONSE',
         `Failed to add server peer due to HTTP status code ${response.status}`
       )
     }
@@ -344,7 +348,8 @@ export class MemberApi extends TypedEmitter {
       )
       return { serverDeviceId: responseBody.data.deviceId }
     } catch (err) {
-      throw new Error(
+      throw new ErrorWithCode(
+        'INVALID_SERVER_RESPONSE',
         "Failed to add server peer because we couldn't parse the response"
       )
     }

test-e2e/server.js

@@ -55,7 +55,10 @@ test('invalid base URLs', async (t) => {
     invalidUrls.map((url) =>
       assert.rejects(
         () => project.$member.addServerPeer(url),
-        /base url is invalid/i,
+        {
+          code: 'INVALID_URL',
+          message: /base url is invalid/i,
+        },
         `${url} should be invalid`
       )
     )
@@ -79,6 +82,7 @@ test("fails if we can't connect to the server", async (t) => {
         dangerouslyAllowInsecureConnections: true,
       }),
     {
+      code: 'NETWORK_ERROR',
       message: /Failed to add server peer due to network error/,
     }
   )
@@ -108,6 +112,7 @@ test(
                 dangerouslyAllowInsecureConnections: true,
               }),
             {
+              code: 'INVALID_SERVER_RESPONSE',
               message: `Failed to add server peer due to HTTP status code ${statusCode}`,
             }
           )
@@ -147,6 +152,7 @@ test(
                 dangerouslyAllowInsecureConnections: true,
               }),
             {
+              code: 'INVALID_SERVER_RESPONSE',
               message:
                 "Failed to add server peer because we couldn't parse the response",
             }
@@ -175,6 +181,8 @@ test("fails if first request succeeds but sync doesn't", async (t) => {
         dangerouslyAllowInsecureConnections: true,
       }),
     {
+      // TODO
+      // code: 'INVALID_SERVER_RESPONSE',
       message: /404/,
     }
   )

test/lib/error-with-code.js

@@ -0,0 +1,10 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+import { ErrorWithCode } from '../../src/lib/error-with-code.js'
+
+test('ErrorWithCode', () => {
+  const err = new ErrorWithCode('MY_CODE', 'my message')
+  assert.equal(err.code, 'MY_CODE')
+  assert.equal(err.message, 'my message')
+  assert(err instanceof Error)
+})