fix #513 - TypeError: Cannot read property 'forEach' of undefined

[natevoci]

Added a check for if symbol.declarations is undefined to avoid the exception described in issue #513.

I reproduced this issue when someone added a file to our project that just exported another module.

import { HotkeysTarget } from '@blueprintjs/core';
export default HotkeysTarget;

When debugging I found that with this export the symbol object does not have a declarations property. It just has

{
  checkFlags: 0,
  flags: 134217732
  name: "unknown"
  type: {checker, flags: 1, id: 3, intrinsicName: "unknown"}
}

so I have just added a condition so that we don't try and call forEach on declarations if it doesn't exist.

[TobyColeman]

Any movement on this? Experiencing the same problem

[buschtoens]

@TobyColeman Take a look at the recent comments in #513. 😉