where did this happen? i'm the artist for the game and we don't want any soft-lock possibilities. if you were actually stuck then we can update the game to remove the possibility of a soft-lock in that area. this will be easier for us rather than updating all the puzzles to not be broken by a respawn key
in the tunnel with the third gravity sword, just after the pit with the spiked walls.
also found another soft-lock: if you fall down to the right from the ledge where the first dash sword is found, then you won't be able to take it to the first barrier. (possible solution: place right-side floor higher so that a loaded down double-jump can clear it)