In _fle2_finalize in mongocrypt-ctx-encrypt.c, there are two potential  memory leak errors that occur:

1. The error case on line 1663 (as of commit 2ec9c3) should bson_destroy the converted and deleteTokens instances but is not currently doing so. (It also looks like the error case should return _mongocrypt_ctx_fail (ctx) instead of false in this case.)
2. bson_copy_to on line 1617 (as of commit 2ec9c3) requires that the destination argument is an uninitialized bson_t (documentation) but line 1616 calls bson_init on the destination converted.

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To reproduce, use

mkdir cmake-build && cd cmake-build
cmake ../
make
valgrind --leak-check=full ./test-mongocrypt