WowAce

I'm not sure if this is new to version 10 of WoW, but the call to UnitReaction that gets called inside of LNR_Private.RawGetPlateType is capable of returning nil (in my case, it was when using the Better Fishing addon to double-click cast into a fish pool), causing an exception when reaction is checked against the various numeric values.  I should probably also mention that my version of LibNameplateRegistry comes from having H.H.T.D. installed.

I fixed it by enclosing the numeric checks inside a nil check on reaction, like so

    if reaction then
        if reaction > 4 then
            reaction = 'FRIENDLY';
        elseif reaction > 2 then
            reaction = 'NEUTRAL';
        else
            reaction = 'HOSTILE';
        end
    end

 This seems to work for my test case, but I'm not sure if all callers of LNR_Private.RawGetPlateType are able to handle the nil return.