Cannot abort save before object exists

[toomim]

This server code crashes:

bus = require('./statebus').serve({file_store: false})
bus('foo').to_save = (o, t) => {t.abort()}

When you do this in a client:

save({key: '/foo', _: 3})

Because the t.abort() implementation currently assumes that the object exists in the cash. We get this stacktrace:

No obj undefined
TypeError: Cannot read property 'key' of undefined
    at Function.save.abort (statebus.js:222:27)
    at Object.t.abort (statebus.js:792:30)
    at c.to_save (test.js:6:19)
    at statebus.js:841:31
    at funk (statebus.js:959:35)
    at Function.run_handler (statebus.js:897:16)
    at bus.route (statebus.js:908:17)
    at Function.bus.route (statebus.js:1754:20)
    at Function.save (statebus.js:141:36)
    at SockJSConnection.<anonymous> (server.js:339:26)
events.js:182
      throw er; // Unhandled 'error' event
      ^