How do I fix a ticking-tile entity?

Solution 1:

This is caused by the bug MC-146246, which is new in this snapshot. Crashes are usually fixed pretty fast, so it's likely that you will be able to use worlds with active conduits soon again.

Since NBTExplorer opens the world just fine for me (using Mono on Linux, not the Mac version), I've removed the two conduit tile entities (at 0 64 -9 and 16 58 -18) for you, making the world temporarily playable again. Then I opened the world and carefully removed the blocks as well, because many things can restore tile entities, which would crash the world again. The world now runs well again.

(download removed)

Update: In 19w12b this bug should be fixed, so you should be able to open world with active conduits again.