Remove 'Copy' from Claim context-menu; Do nothing when menu is blank.
Remove 'Copy' from Claim context-menu; Do nothing when menu is blank.

'Copy' is always disabled for the case of Claim previews since no text is selected. User cannot select text anyway since a left-up event would invoke the Claim's `click` event. 'Copy' is there simply because of re-using `openContextMenu`.

lbryio/lbry-app,lbryio/lbry-app