Relatively Small Repro for Crashing FTS5 in Sqlite

00-fts5-crash-repro.sql

CREATE VIRTUAL TABLE x USING fts5(content);
INSERT INTO x(x, rank) VALUES('pgsz', 32);

# Repeat next three lines 2000 times
INSERT INTO x(content) VALUES('hello world');
INSERT INTO x(content) VALUES('how are you');
INSERT INTO x(x, rank) VALUES('optimize', 1);

# If you repeat them less - you can below to see
# what's actually going in the FTS5 index.
SELECT fts5_decode(rowid, block) FROM x_data WHERE rowid IS 10;

01-output.txt

{structure} {lvl=0 nMerge=0 nSeg=0} {lvl=1 nMerge=0 nSeg=0} {lvl=2 nMerge=0 nSeg=0} {lvl=3 nMerge=0 nSeg=0} {lvl=4 nMerge=0 nSeg=0} {lvl=5 nMerge=0 nSeg=0} {lvl=6 nMerge=0 nSeg=0} {lvl=7 nMerge=0 nSeg=1 {id=4 leaves=1..4}}