Don't update zoom to undefined on setId

[will-moore]

Fixes a bug introduced in #527: On Edit ID the panel zoom is updated to undefined since the incoming image data has no zoom info so data.zoom is always undefined.

This results in rendering errors - e.g. Zoom slider 0 and other NaN values below:

To test:

• Zoom a panel, then Edit ID to replace image with another.
• The zoom should remain unchanged and after de-selecting and re-selecting the panel (to trigger update of right panels) the zoom controls, viewport x, y, width, height etc should be rendered correctly.

cc @Rdornier

[will-moore]

@jburel - Any idea what's failing in the above job? Seems that npm isn't installed.

Same error on #549 (and I assume on all other PRs when they next try to run checks):

+ python setup.py sdist
running sdist
npm install
error: command 'npm' failed: No such file or directory

Thanks

[Rdornier]

I can indeed reproduce the bug.
I didn't thought about testing this feature when I added this feature.
Thanks for reporting and fixing it.

[pwalczysko]

Reproduced on demo (without this PR). See it fixed on merge-ci.

[will-moore]

Released in omero-figure 6.2.1