Instant Death with Nothing in Combat Log

Is there some damage hack where people can instantly kill you and show nothing in the combat log? I was in darkshire once and then half an hour later near the FP in redridge going back into elwynn forest, I was running along and instantly killed from full health, lvl 29 pally, nothing shows in the combat log as hitting me it shows some character cast vanish, same person refreshed master of subtlety, same person gains stealth, my warhorse fades, I die... But nothing hitting me for damage or showing damage in my damage taken on details. I'm new on this server is this some bug or am I missing something?

The first time it happened the log says someone hit me for 4 damage melee lol but I died from full hp, I don't get it.

In my experience combat log does not show hit from stealth. You were probably hit by ambush by a rogue in stealth which killed you instantly or in case of one with 4 hp hit, you were left with 4 hp after ambush and melee swing killed you.
I have no idea if attacks from stealth not showing in combat log is bug or not. Frustrating for sure, though.

Ah thank you for the clarification! I was wondering if getting 1-hit from stealth of from out of combat would actually put you into combat and log anything or you would just die right out, I'm sure it was some rogue just camping down there then xD