No Exception thrown when there is a constraint violation, and delete fails

I am trying to do a delete, and there seems to be a constraint violation.
Fine, but why does it not send an exception to let me know this.
I mean, nothing happens. Not even a warning.

Is there something I need to turn on to find constraint violations as exceptions?

Code:
Connection c = DriverManager.getConnection(
c.setAutoCommit(true);

PreparedStatement pst = c.prepareStatement("delete from queue where id=?");
pst.setInt(1, 850);
pst.executeUpdate();

c.close();

Exception:
None, not a thing.

Error Log:

ERROR: update or delete on "queue" violates foreign key constraint "fkd73c6034ba977309" on "branch_queue"
DETAIL: Key (id)=(850) is still referenced from table "branch_queue".