Validator crashes on 0 node highway

[Gnonthgol]

Steps to reproduce:

1. Start out with a clean JOSM instance version 5356 and 5369 are confirmed to have this problem.
2. Open a .osm file that includes a way with 0 nodes and a "highway" tag.
3. Click the "Validate" button in the validation window or try to upload the file.

Expected result:
Validator should give a strong and clear message that there is a problem and upload should be haulted.

Actual result:
JOSM throws the following exception and stops the upload without any clear error messages.

java.lang.NullPointerException
	at org.openstreetmap.josm.data.validation.tests.WayConnectedToArea.visit(WayConnectedToArea.java:29)
...

[Gnonthgol]

Minimal test file that trigers the bug

[mrwojo]

Closed as duplicate of #7465.
Thanks for the test file. See #7465.