Vertical cursor navigation is broken sporadically

[Rufflewind]

Normally, if I (deliberately) move the cursor at the beginning of a line (column 0) and go downward (or up) with C-n or ↓, it will stay at column 0 forever.

But sometimes, after using haskell-mode for some time, a glitch occurs that causes the cursor to be reset to some random column j after any vertical movement. Even if I return to column 0 it will still keep resetting it back to column j whenever I move up or down.

Reloading the buffer fixes this, but it always reappears after some time.

FWIW I'm using haskell-mode 13.14.2 with haskell-indentation.

[Rufflewind]

Never mind. It's not really related to haskell-mode. I think it's the result of accidentally hitting C-x C-n (set-goal-column).