Assertion failed: Should be a finite Vector2

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I'm seeing this error in master when returning a vector to its toolbox.

assert.js?bust=1572284237284:22 Uncaught Error: Assertion failed: Should be a finite Vector2
    at window.assertions.assertFunction (assert.js?bust=1572284237284:22)
    at VectorNode.setTranslation (Node.js?bust=1572284237467:2263)
    at VectorNode.set translation [as translation] (Node.js?bust=1572284237467:2272)
    at VectorNode.updateVector (RootVectorNode.js?bust=1572284237467:139)
    at RootVectorNode.js?bust=1572284237467:108
    at listener (Multilink.js?bust=1572284237467:41)
    at TinyEmitter.emit (TinyEmitter.js?bust=1572284237467:68)
    at DerivedProperty._notifyListeners (Property.js?bust=1572284237467:265)
    at DerivedProperty.set (Property.js?bust=1572284237467:176)
    at listener (DerivedProperty.js?bust=1572284237467:66)

Steps to reproduce:

1. Start sim with ?ea
2. Go to _Explore 1D` screen
3. Drag vector 'a' from tool box, drop it on the graph.
4. Drag vector 's' from graph, drop it on toolbox.

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This also occurs in 1.0 branch with the same set of RC fixes, so it's probably one of those fixes that introduced this.

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Bisecting shows that this bug was introduced in 35bfd34 for #250 (use rectangular pointer areas for vectors toolbox icons).

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Fixed in master and 1.0 branches in the above commits. I've also associated these commits with related issue #250, so I'm going to close this issue. Not sure how this change happened, possibly because I was not on my usual development machine.