Here is an update from another user regarding my above post.
The problem with LibHealComm 4.0 throwing an error seems to be caused by Visual Heal versions 10.2 and 10.3.
Those of you having a problem caused by the LibHealComm 4.0 error, check your version of Visual Heal. You may nootice that not only are you getting the error, but if you are using Visual Heal v10.3, the Visual Heal main bar will not show (the error occurs during loading). With Visual Heal v10.2, the error occurs whenever you cast a heal using Healbot. I never tried casting a heal without Healbot.
I would like to say: Great Addon! However, there seems to be a bug with either Healbot 188.8.131.52 or the new LHC4. It happened when we were in ulduar 25 on Yogg.
LibHealComm-4.0-37 (HealBot):1050: attempt to perform arithmetic on upvalue 'activeGraceModifier' (a nil value)
LibHealComm-4.0-37 (HealBot):2089: in function `?'
LibHealComm-4.0-37 (HealBot):2509: in function <...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:2508>
I see your looking at HoTs and a fix for missing GUID's, so maybe this is already fixed.
It was posted as a comment by a healbot user on the Cursed forum.
I am assuming he is using r1.4 of LHC40, I asked him to confirm the version.
Message: ...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:85: bad argument #9 to 'format' (number expected, got no value)
Time: 10/15/09 16:45:32
Stack: [string "Interface\FrameXML\BasicControls.xml:<Scrip..."]:18: in function <[string "Interface\FrameXML\BasicControls.xml:<Scrip..."]:4>
(tail call): ?
[C]: in function `format'
...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:85: in function <...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:82>
...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:1645: in function <...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:1643>
...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:1669: in function <...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:1663>
...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:1976: in function `?'
...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:2509: in function <...Ons\HealBot\Libs\LibHealComm-4.0\LibHealComm-4.0.lua:2508>
I get this error when I heal someone in my group (I was healing a NE Druid lvl 19)