column "b" is of type X but expression is of type text

A third party application we use generates SQL queries.  Here is query it generated that broke today and for which I have a hard time arguing that the postgres behavior is correct (minimally the error message is confusing):

=# create temporary table foo (b double precision );
CREATE TABLE
Time: 40.368 ms
=# insert into foo select min(NULL);
ERROR:  column "b" is of type double precision but expression is of type text
LINE 1: insert into foo select min(NULL);
                               ^
HINT:  You will need to rewrite or cast the expression.