errmsg("... because ...")

Hackers,

There are a bunch of error messages saying something like

"cannot foo because bar"

For example,

errmsg("cannot assign to field \"%s\" of column \"%s\" because its type %s is not a composite type")

What do you think of changing those to use errdetail in addition to
errmsg?  So this particular example would become something like

errmsg("cannot assign to field \"%s\" of column \"%s\"),
errdetail("Its type %s is not a composite type.")


There are some of them that should probably be left alone, like

errmsg("terminating connection because of crash of another server process")

I see around a dozen messages in the backend that could be changed like
this.

-- 
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"La gente vulgar solo piensa en pasar el tiempo;
el que tiene talento, en aprovecharlo"