New error_log message from 2.2.13 (Apache Users)

in which everything mentioned is new except OpenSSL.

It has been running fine, but there are a few messages in error_log, of a type not seen before:

[Fri Sep 04 23:15:52 2009] [error] [client 68.13.227.175] Handler for type-map returned invalid result code 53, referer: http://www.stumbleupon.com//refer.php?url="">
... [04/Sep/2009:23:15:52 -0700] "GET /1n/walrus.jpg HTTP/1.1" 500 - "http://www.stumbleupon.com//refer.php?... "Mozilla/4.0 (compatible; MSIE 7.0;..."

[Sat Sep 05 12:28:31 2009] [error] [client 68.49.95.123] Handler for type-map returned invalid result code 53, referer: http://www.animalhead.com/namricns.html
... [05/Sep/2009:12:28:31 -0700] "GET /1n/puma.jpg HTTP/1.1" 500 - "http://www.animalhead.com/namricns.html" "Mozilla/4.0 (compatible; MSIE 8.0; ...

[Sat Sep 05 17:09:53 2009] [error] [client 98.224.21.166] Handler for type-map returned invalid result code 53, referer: http://www.animalhead.com/cheelnks.html?_
... [05/Sep/2009:17:09:53 -0700] "GET /1n/berbr.jpg HTTP/1.1" 500 - "http://www.animalhead.com/cheelnks.html?_" "Mozilla/5.0 (Windows; U; Windows NT 6.0; ..."

In each pair of lines, the 1st is from error_log while the 2nd is from access_log (abbreviated).

All of the errors occurred on requests for jpg thumbnails that are cached by conf statements like these:

CacheFile /usr/local/apache2/htdocs/1n/aardvark.jpg
CacheFile /usr/local/apache2/htdocs/1n/anteater.jpg

The error handling is stock Apache; the httpd.conf file was carried over from earlier versions of 2.2, and includes:

Alias /error/ "/usr/local/apache2/error/"

<Directory "/usr/local/apache2/error">
   AllowOverride None
   Options IncludesNoExec
   AddOutputFilter Includes html
   AddHandler type-map var
   Order allow,deny
   Allow from all
   LanguagePriority en cs de es fr it ja ko nl pl pt-br ro sv tr
   ForceLanguagePriority Prefer Fallback
</Directory>

ErrorDocument 400 /error/HTTP_BAD_REQUEST.html.var
ErrorDocument 401 /error/HTTP_UNAUTHORIZED.html.var

...

The only mod_perl2 handler that is invoked for a .jpg file is a fixup handler, and it for sure :) only returns OK.

Are such errors familiar to anyone? Is there anything I can do to eliminate them?

Thanks,

cmac