My call to sqlite3_bind_zeroblob64() fails with SQLITE_TOOBIG,
yet sqlite3_errmsg() returns "not an error". And I am calling
sqlite3_errcode() and sqlite3_errmsg() right after than too big error.

A quick look at the code, seems to confirm this API does not set
db->errCode like other binds do, via vdbeUnbind(). This seems to
violate the contract of https://www.sqlite.org/c3ref/errcode.html:

If the most recent sqlite3_* API call associated with database
connection D failed, then the sqlite3_errcode(D) interface returns
the numeric result code or extended result code for that API call.

Simple oversight? Thanks, --DD