fix: remove replication error when core is closed

If a core is closed, we can't replicate it.

This can happen if you leave a project while offline, then reconnect. I
added a test for this case and fixed the issue. (The fix is just one
line, but it took a whole day to figure that out.)

Fixes [#584].

[#584]: #584

src/sync/peer-sync-controller.js

@@ -229,6 +229,7 @@ export class PeerSyncController {
    * @param {import('hypercore')<'binary', any>} core
    */
   #replicateCore(core) {
+    if (core.closed) return
     if (this.#replicatingCores.has(core)) return
     this.#log('replicating core %k', core.key)
     core.replicate(this.#protomux)

test-e2e/project-leave.js

@@ -284,4 +284,48 @@ test('Data access after leaving project', async (t) => {
   await disconnectPeers(managers)
 })
 
+test('leaving a project while disconnected', async (t) => {
+  const managers = await createManagers(2, t)
+
+  let disconnectPeers = connectPeers(managers)
+  t.teardown(() => disconnectPeers())
+
+  await waitForPeers(managers)
+
+  const [creator, member] = managers
+  const projectId = await creator.createProject({ name: 'mapeo' })
+
+  await invite({
+    invitor: creator,
+    invitees: [member],
+    projectId,
+    roleId: MEMBER_ROLE_ID,
+  })
+
+  const projects = await Promise.all(
+    managers.map((m) => m.getProject(projectId))
+  )
+  const [creatorProject] = projects
+
+  await disconnectPeers()
+
+  await member.leaveProject(projectId)
+
+  t.ok(
+    await creatorProject.$member.getById(member.deviceId),
+    'creator still thinks member is part of project'
+  )
+
+  disconnectPeers = connectPeers(managers)
+  await waitForPeers(managers)
+
+  await waitForSync(projects, 'initial')
+
+  t.is(
+    (await creatorProject.$member.getById(member.deviceId)).role.roleId,
+    LEFT_ROLE_ID,
+    'creator no longer thinks member is part of project'
+  )
+})
+
 // TODO: Add test for leaving and rejoining a project