Conditional instances are not properly handled by the WebIDE, crashing
Try this ksy file - it shows "inst1" but it should not, and clicking on it leads to an exception.

	meta:
	  id: bug_cond_instance
	  title: Demonstrates a parsing bug in the WebIDE (0.7 and 0.8-devel)

	seq:
	- id: start
	  size: 1
	instances:
	  inst1:
		pos: 2
		if: false
		size: 1
		doc: this instance must not appear in the IDE but it does, and crashes if selected
	  inst2:
		pos: 3
		if: true
		size: 1

Here's the error msg:

> Parse error (Error): primitiveToText: object is not primitive!
> Call stack: Error: primitiveToText: object is not primitive!
>     at ParsedTreeHandler.primitiveToText (https://ide.kaitai.io/devel/js/v1/parsedToTree.js:75:23)
>     at ParsedTreeHandler.childItemToNode (https://ide.kaitai.io/devel/js/v1/parsedToTree.js:140:106)
>     at valuePromise.then.valueExp (https://ide.kaitai.io/devel/js/v1/parsedToTree.js:257:49)
>     at <anonymous> Error: primitiveToText: object is not primitive!
