Fix: event-expr-to-bytecode: use after free in logging on error

1448709 Use after free

This could cause an immediate crash or incorrect values might be read
subsequently resulting in incorrect computations.

In event_expr_to_bytecode_recursive: A pointer to freed memory is
dereferenced, used as a function argument, or otherwise used (CWE-416)

Reported-by: Coverity Scan
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ifde0e21dbf6bf08be07b38f9c38896bdce973132