take_diag corrupts memory

[wavepacket]

Just tried something along these lines:

RTensor matrix = ...
RTensor couplings = take_diag(matrix, 1);
RTensor frequencies = take_diag(matrix, 0, 1); // skip the first frequency

As soon as I add the last line, I get a memory corruption when exiting the context (i.e., when the matrices are deleted). This suggests some issue with take_diag() if you supply the start/end point.

[wavepacket]

Just tried it again: Could not verify (assertion fails instead).
Besides I noticed that I used this incorrectly.