Highlight affected relation members in validation warnings

[naoliv]

Validate the attached file and see a warning about Role verification problem - Role unknown in templates /forward/link/backward

See that it seems that there is one role with one or more whitespaces, which is not so easy to find.

Could we have some way to somehow highlight the affected relation member in cases like this, please?

JOSM:

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-01-15 23:55:54 +0100 (Sun, 15 Jan 2017)
Build-Date:2017-01-16 02:33:13
Revision:11465
Relative:URL: ^/trunk

Identification: JOSM/1.5 (11465 pt_BR) Linux Debian GNU/Linux testing (stretch)
Memory Usage: 390 MB / 10206 MB (105 MB allocated, but free)
Java version: 1.8.0_111-8u111-b14-3-b14, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1600x900, :0.1 1280x1024
Maximum Screen Size: 1600x1024
Java package: openjdk-8-jre:amd64-8u111-b14-3
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-13
VM arguments: [-Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found

[Don-vip]

In 15418/josm:

fix #14253 - Highlight affected relation members in role validation warnings