Refine a lostAccount test

test/unit/idStore-migration-test.js

@@ -83,7 +83,7 @@ describe('IdentityStore to KeyringController migration', function() {
       keyringController.configManager.setWallet('something')
       const state = keyringController.getState()
       assert(state.isInitialized, 'old vault counted as initialized.')
-      assert.equal(state.lostAccounts.length, 0, 'no lost accounts')
+      assert(!state.lostAccounts, 'no lost accounts')
     })
   })
 })