I'm stuck trying to debug the LG TV Webos browser which is a chromium browser (chrome version 38) i've tried Ghostlab, weinre but they dont show any errors in console.
I'm leaving this just as reference since question is old, in case somebody can find this tip helpful since i've been through a lot of trouble to find any kind of infos about WebOS developing.
Env info
I'm developing on Mac, and running app on webOS TV 5.x versions, packaged and installed on physical device via WebOS CLI (Note: there are 2 CLI available, the other one is for WebOS OSE @webosose/ares-cli that isn't supported in my case).
TL;DR Thats my fix
I've "solved" (see note2) my problem downloading an old chromium version (68), setting it as default browser (on Mac system settings) and then building/running the app + running the inspection.
So far i haven't found an alternative to specify the browser directly in ares-inspect command instead of setting it as default system browser, but i haven't put any effort trying to solve the problem since it wasn't troubling me at all.
Notes
Note 1: Building/running + inspection means that the following ares commands are executed in series on the same device (see CLI docs for ares usage details) ares-package->ares-install->ares-launch->ares-inspect
Note 2: On some device (can be the older ones but i'm not sure since i can't determine exactly mine devices infos) html inspector doesn't work properly, it's possible to see dom elements, opening them only via double click, but they are not selectable therefore no css info can be inspected, i've no fix available for this problem. Only some device have this problem in some case inspector is just working fine. Console is working fine in all cases though.
No need to say that this is an hack to make things work in a "decent way", it isn't for sure a good practice... Even though "finding hack to make things works" sums up pretty well my entire experience on smart TV developing.