For some emails, notmuch-vim crashes. I can't figure out the reason for
this. The stack trace is:

Error detected while processing function
<SNR>13_search_show_thread[10]..<SNR>13_show:
line   39:
NoMethodError: undefined method `mime_type' for nil:NilClass
eval:22:in `block (2 levels) in <main>'
eval:8:in `each'
eval:8:in `block in <main>'
eval:323:in `render'
eval:4:in `<main>'
eval:8:in `command'
eval:8:in `<main>'

The error seems to only come up for multi-mime emails, but then also not
all of them. It seems like the error is that find_first_text returns nil,
but that can only happen if the message doesn't have any content-type
"text/plain" or "text/html" AFAICT, but I checked: It does both. GMail
doesn't have any problems reading that same email.

Any ideas? Thanks.

- Nicolas