ERROR: negative bitmapset member not allowed in SELECT

Hi everyone,

the following statements results in an error "ERROR:  negative
bitmapset member not allowed", which is unexpected:

CREATE TABLE t0(c0 serial, c1 boolean);
CREATE STATISTICS s1 ON c0, c1 FROM t0;
INSERT INTO t0(c1) VALUES(TRUE);
ANALYZE;
CREATE INDEX i0 ON t0(c0, (t0.c1 AND t0.c1));
SELECT * FROM (SELECT t0.c0 FROM t0 WHERE (((t0.c1) AND (t0.c1)) OR
FALSE) IS TRUE) as result WHERE result.c0 IS NULL; -- unexpected:
ERROR:  negative bitmapset member not allowed

When replacing serial by integer, I instead get "ERROR:  type with OID
21938 does not exist".

I'm using the following Postgres version: 12beta2 (Debian 12~beta2-1.pgdg90+1).

Best,
Manuel