How to capture error message and save to a table in PostgreSQL?

Hi, All,

I wish to test out to produce a table when data violates constraints when
insert into a new table with constraint set. How to capture and save error
message to a new table?

INSERT INTO test3 ("Record Type", "Unique Reference Number", "Supplier
Reference Number", "Post Code")
SELECT "Record Type", "Unique Reference Number", "Supplier Reference
Number", "Post Code" from test;

ERROR: new row for relation "test3" violates check constraint "test3_Post
Code_check"
DETAIL: Failing row contains (L, 14986526, 1207174, null, null, null,
null, null, null, SURREY, null, null, null, null, null, null, null, null).
SQL state: 23514

Regards,
David