Consider the following test case:

<pre>
CREATE VIRTUAL TABLE vt0 USING fts4(c0, prefix=1);
BEGIN;
INSERT INTO vt0 VALUES (0);
INSERT INTO vt0(vt0) VALUES('optimize');
INSERT INTO vt0(vt0) VALUES('integrity-check'); -- database disk image is malformed
</pre>

The integrity-check results in an error "database disk image is malformed", which is unexpected.