cppcheck flagged a possible null deref of inst2 at line 390. The early
'if (seq->count == 1) return NULL;' makes the loop run at least once
in the reachable path, so inst2 is set; the warning is a false positive
for cppcheck's analysis.

Refactor to drop the post-loop reference to inst2 entirely: after the
loop body, inst1 has been advanced to the same instant inst2 pointed
to (inst1 = inst2 at end of body), so use inst1->t for the final
timestamp. Move inst2 declaration into the loop where it's actually
written.

GHAS code-scanning alert MobilityDB#742 (PR MobilityDB#740 review) goes away with this.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>