Implement our own error handler for db2_prepare
Implement our own error handler for db2_prepare

db2_prepare() may issue a [warning][1] in addition to returning false.
If you have an error handler set (e.g. in the Expressive pipeline) then
the message created is "db2_prepare(): Statement Prepare Failed" which
is not helpful.

Therefore, we create our own error handler and trap this ourselves so
that we can throw an ErrorException with more information from
db2_stmt_errormsg().

[1]: https://github.com/php/pecl-database-ibm_db2/blob/df913feb4dff56366ac4656b0bb6b39200794bde/ibm_db2.c#L4400

zendframework/zend-db,zendframework/zend-db