fix(cursor): Remove stale cursor from config.cson when cursor error

- #2049

internal_packages/worker-sync/lib/nylas-long-connection.coffee

@@ -111,6 +111,7 @@ class NylasLongConnection
           res.on 'data', (chunk) =>
             if chunk.toString().indexOf('Invalid cursor') > 0
               error = new Error('Delta Connection: Cursor is invalid. Need to blow away local cache.')
+              NylasEnv.config.removeAtKeyPath("nylas.#{@_account.id}.cursor")
               DatabaseStore._handleSetupError(error)
             @close()
           return