Undefined index in get_extension_mimetype() (line 1230 of modules\media\media.module).

I get a Undefined index (whatever the mime-type is) in get_extension_mimetype() (line 1230 of modules\media\media.module) error.

This happens because I entered an incorrect mime-type when attaching a file field to an entity, in its 'Allowed file extensions for uploaded files'. Perhaps this field should get some form of validation, or the media module must just do a few type checks, as in:

media.module (line 1230)
replace:
if ($id = $mimetype_mappings['extensions'][$extension]) {
return $mimetype_mappings['mimetypes'][$id];
}

with:
if (isset($mimetype_mappings['extensions'][$extension])) {
return $mimetype_mappings['mimetypes'][$mimetype_mappings['extensions'][$extension]];
}

and, media.media.inc (line 86)

replace :
foreach ($extensions as $extension) {
$mimetype = media_get_extension_mimetype($extension);
$mimetypes[] = $mimetype;
}

with:
foreach ($extensions as $extension) {
$mimetype = media_get_extension_mimetype($extension);
if ($mimetype) {
$mimetypes[] = $mimetype;
}
}