Fixed #33160 -- Avoided suppressing query errors in _nodb_cursor() on PostgreSQL.

[blueyed]

https://code.djangoproject.com/ticket/33160

[felixxm]

@blueyed Thanks for this patch 👍 Can we add a small test? e.g.

    def test_nodb_cursor_reraise_exceptions(self):
        with self.assertRaisesMessage(DatabaseError, 'exception'):
            with connection._nodb_cursor() as cursor:
                raise DatabaseError('exception') 

[blueyed]

@felixxm
Sure, thanks for the test - pushed slightly modified.

btw: previously it would also throw RuntimeError("generator didn't stop after throw()") in this case, since it first yielded, then got the exception, and yielded again - while it is only meant to yield once, which is fixed by this patch.

[felixxm]

@blueyed Thanks 👍