Display the line number of wrong MapCSS rule

[naoliv]

While writing some local rules I was seeing this in JOSM:

2017-09-21 10:36:19.611 INFORMAÇÕES: Source Brasil has been modified. Reloading it...
2017-09-21 10:36:19.628 GRAVE: Cannot add MapCss rule: java.lang.IllegalArgumentException: Unexpected '='. Please only specify the key to remove!

It took a while to find that I was using a wrong fixRemove: "key=value";

Could JOSM say, if possible, the line number where the problem is?

JOSM:

Build-Date:2017-09-21 09:18:11
Revision:12882
Is-Local-Build:true

Identification: JOSM/1.5 (12882 SVN pt_BR) Linux Debian GNU/Linux testing (buster)
Memory Usage: 914 MB / 6372 MB (492 MB allocated, but free)
Java version: 1.8.0_144-8u144-b01-1-b01, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1600x900, :0.1 1280x1024
Maximum Screen Size: 1600x1024
Java package: openjdk-8-jre:amd64-8u144-b01-1
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]

not possible to include the line, but at least we can include the mapCSS directive.

[Don-vip]

In 12883/josm:

fix #15341 - better error message