Additional defenses (above and beyond [b986600520696b0c]) to prevent an

invalid subquery from causing problems downstream.  If an error is found
while analyzing a subquery expression, change the expression to TK_ERROR
so inhibit further processing on that expression.
dbsqlfuzz cf624b8c0484c66e0f552bf6475e3e3f2c22b24e.

FossilOrigin-Name: 0be6b6c9f7c562e764792a4a5eb53ed11b230174b19361f7cd7778c743314bbd