Dynamically changed Handles cause a break

Hey! First off let me say thanks for creating this awesome package!

I have different NodeTypes that have different amount of <Handles/> on them. There is one component in particular that you make some selections, and based off the selections you make, it changes the elements type. The re-rendering happens and everything looks as it should, but when you select a Handle, it errors out.

I’ve been able to trace it to:

1. The Node originally renders with 0 Handles.
2. Make sidebar selections.
3. Node changes type to where it now has 2 Handles.
4. Those handles can no longer be connected and error out.

The error I receive is:

ReactFlow.esm.js:7195 Uncaught TypeError: Cannot read property '0' of null
    at ConnectionLine (ReactFlow.esm.js:7195)
    at renderWithHooks (react-dom.development.js:14826)
    at updateFunctionComponent (react-dom.development.js:17059)
    at beginWork (react-dom.development.js:18644)
    at HTMLUnknownElement.callCallback (react-dom.development.js:189)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:238)
    at invokeGuardedCallback (react-dom.development.js:293)
    at beginWork$1 (react-dom.development.js:23235)
    at performUnitOfWork (react-dom.development.js:22186)
    at workLoopSync (react-dom.development.js:22162)
    at performSyncWorkOnRoot (react-dom.development.js:21788)
    at react-dom.development.js:11112
    at unstable_runWithPriority (scheduler.development.js:653)
    at runWithPriority$1 (react-dom.development.js:11062)
    at flushSyncCallbackQueueImpl (react-dom.development.js:11107)
    at flushSyncCallbackQueue (react-dom.development.js:11095)
    at flushPendingDiscreteUpdates (react-dom.development.js:21879)
    at flushDiscreteUpdates (react-dom.development.js:21859)
    at flushDiscreteUpdatesIfNeeded (react-dom.development.js:1095)
    at dispatchDiscreteEvent (react-dom.development.js:4168)```

[underGhost]

Thanks @moklick! Looks like that fixed my issue. Appreciate you getting to it so fast!

[underGhost]

Thanks so much!

Yea I started to trace it down and it looks like, we querySelectorAll for the Handles only once. If it happened whenever the type changed then it would probably fix it.