Oh man, the white mold panic is real. I saw this thing on a fermentation forum a while back where someone broke down the difference between kahm yeast and actual mold and it basically came down to texture. Kahm yeast is usually flat, kind of powdery or wrinkly looking and doesn't really have fuzz to it. Mold will look fuzzy or hairy and sometimes has little dots of color like green or black. If it's that solid white layer that just sits on top and isn't fuzzy, you're probably good. I'd say if you skimmed it off and the liquid underneath smells like normal tangy sauerkraut and not like rotting garbage, you can probably save it. Just make sure everything below the surface is submerged in the brine and try not to open the jar too much to check on it.
Gotta admit, I used to be one of those people who'd toss the whole batch the second I saw any white stuff on top. This actually makes a lot of sense though, especially the part about texture vs fuzz. Might try saving my next jar if it's just kahm.