The patch causes an informative error message to be reported for src 
blocks like this (no language):

#+begin_src
(+ 1 2)
#_end_src

when exporting instead of failing with a cryptic error message.

Arguably, it would be better to skip the malformed src block as 
`org-babel-map-src-blocks' does or (as per John's message) 
org-babel-tangle does.

WDYT?

Chuck


On Tue, 10 Mar 2015, Charles Berry wrote:

> XIE Yuheng <xyheme <at> gmail.com> writes:
>
>>
>>
>> Bug: org-babel-parse-src-block-match reporting "Wrong type argument:
>> stringp, nil" when exporting a org-mode file with a lots of code blocks
>> [8.3beta (release_8.3beta-895-g375c83  <at>
>> /usr/share/emacs/site-lisp/org/)]
>>
>> the following is *Messages* buffer
>>    https://www.refheap.com/98243
>> the following is the org-mode file with a lot of code blocks
>>    https://github.com/the-little-language-designer/cicada-nymph/blob/
> master/cicada-nymph.org
>
>
> Look at the *Messages*  buffer and you will see a list of src blocks that were
> processed without error.
>
> The src block *after* the last block in the list (before the error message)
> caused the error.
>
> `org-babel-parse-src-block-match' expects a language for a src block.
>
> Specify a language for every src block and it will export.
>
> HTH,
>
> Chuck
>
>
>