Well, not *completely*, just mostly :)

Go to https://www.mediawiki.org/w/index.php?title=VisualEditor:TestReferenceContents&veaction=edit and select reference [3] by clicking on it, then press Ctrl+C. You'll get a JS error.

There are several things wrong here:

In findEndOfNode() inside of ve.dm.Converter.prototype.getDomSubtreeFromData:
* Line 1172 tries to throw an error using dataElement.type, but dataElement isn't set anywhere, so the generation of the error itself throws an error

In ve.ce.Surface.prototype.onCopy:
* On line 693, cloneSliceFromRange() returns a slice with unbalanced data: [ {type:'paragraph'}, {type:'mwReference'}, {type:'/mwReference'}, {type:'internalList'}, ..., {type:'/internalList'} ]

In ve.dm.Document.prototype.cloneSliceFromRange:
* On both lines 378 and 431, selectNodes() for a range exactly covering a reference returns the text node as well. In my test case, the return value is [ { node: TextNode, range: [69,69] }, { node: ReferenceNode } ]. This is clearly a bug in selectNodes()
* Even if selection was correctly set to something of length 1, line 388 does not allow for selection[0].range to be undefined, but that's actually expected when a node is completely selected. This case should be handled, and selection[0].nodeRange should be checked against range instead in that case. So something like else if ( selection.length === 1 && range.equalsSelection( selection[0].range || selection[0].nodeRange ) ) . Otherwise, even if we fixed the selectNodes bug, the selection.length===1 code path still wouldn't be taken.
* Because selection.length>1, the else path is taken, and we populate balanceOpenings and balanceClosings. These two are populated separately in a way that's broken: because the first node is a text node (not wrapped) we add an opening for that node's parent, but because the second node is a reference node (wrapped), we don't add a closing after it. The result is unbalanced output. This code seems to wrongly assume that leaf nodes are always unwrapped.