Zooming out from a labelled subtree does not correctly update the URL query

[jameshadfield]

Current Behavior
Clicking on the root branch of a displayed subtree zooms out (in the tree). If the currently zoomed-to branch has a label set, then this is displayed in the URL query as ?label=.... When zooming out from this subtree by clicking on the root, the URL query does not update.

Expected behavior
Upon zooming out from the subtree by clicking on the root, then the label should disappear from the URL query.

How to reproduce
Steps to reproduce the current behavior:

1. Open https://nextstrain.org/staging/test/tree-labels-2020-05-26
2. Click on the branch labelled "string-value" to zoom into the subclade. Observe that the URL query updates.
3. Click on the root branch of the subtree (the left-most bit).
4. We correctly zoom out, however the URL query remains when it should be cleared.

Possible solution
Update the URL (redux) middleware to listen for the appropriate redux action & update the query

Note that pressing "reset layout" when zoomed in does correctly clear the URL query.

Your environment: if browsing Nextstrain online
Auspice 2.15.0

[ktun95]

Hello, I would like to take on this issue, if that's all right.

[jameshadfield]

Wonderful!

P.S. here is the link to the dataset JSON behind the example above which should help with local development.

[ktun95]

Hi! I just made a PR. This is my first one, so I would really appreciate all the feedback I can get, and make any changes necessary.