This line caues that before the closing bracket, an additional comma is written if the max entries limit is hit (whyever this limit exists...). It should be if (i < metadata_entries - 1) if I'm not mistaken. This additional comma causes python to fail reading the json sidecar file.
https://github.com/Psyop/CryptomatteArnold/blob/83831bdaa5703e1dc53592b432cf5ef7fd1b36c3/cryptomatte/cryptomatte.h#L584
This line caues that before the closing bracket, an additional comma is written if the max entries limit is hit (whyever this limit exists...). It should be if (i < metadata_entries - 1) if I'm not mistaken. This additional comma causes python to fail reading the json sidecar file.