pageinspect and hash indexes

While trying to figure out some bloating in the newly logged hash indexes,
I'm looking into the type of each page in the index. But I get an error:

psql -p 9876 -c "select hash_page_type(get_raw_page('foo_index_idx',x))
from generate_series(1650,1650) f(x)"

ERROR: page is not a hash page
DETAIL: Expected 0000ff80, got 00000000.

The contents of the page are:

\xa4000000d8f203bf65c900001800f01ff01f0420...

(where the elided characters at the end are all zero)

What kind of page is that actually? And isn't it unhelpful to have the
pageinspect module throw errors, rather than returning a dummy value to
indicate there was an error?

Thanks,

Jeff