System Information:

compile-time options: CC=clang-12 ./configure --enable-debug
sqlite_source_id: 2022-02-28 13:38:28 f2f0426035d4e0334be000a3eb62bbd7d61fdab7c2ef9ba13cfdf6482396dd13
output: sqlite3: sqlite3.c:50948: void sqlite3PcacheMakeDirty(PgHdr *): Assertion `p->nRef>0' failed.

PoC:

CREATE TABLE t1 ( id REAL PRIMARY KEY CHECK( 'For since by man came death,' IS NOT NULL ) );
CREATE TABLE a(b, c, sqlite_stat1 UNIQUE, PRIMARY KEY(b, c)) WITHOUT ROWID;
INSERT INTO a VALUES('abc', zeroblob(74573), 'xyz');
PRAGMA integrity_check;
INSERT INTO a VALUES('abc2', zeroblob(205), 'xyz2');
PRAGMA writable_schema = 1;
SELECT sqlsim10 FROM sqlsim12 WHERE sqlsim11=='abc';
UPDATE sqlite_master SET rootpage=5 WHERE tbl_name = 'a';
PRAGMA writable_schema=ON;
CREATE VIRTUAL TABLE v4 USING zipfile ( v5 , v6 REAL ) ;
UPDATE a SET sqlite_stat1=sqlite_stat1||'6';
PRAGMA reverse_unordered_selects = ON;
PRAGMA foreign_keys;
COMMIT;
UPDATE a SET b=b||'1';
UPDATE a SET sqlite_stat1=sqlite_stat1||'2';