You can check if a PO file is valid with the following command:

        msgfmt -c -o /dev/null <po file>
      

The following errors were found in yard 's PO files:

gettext: po/ja.po:2408: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:4339: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:5393: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:5422: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:6570: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:7353: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:8690: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:11825: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:11990: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:12015: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:12057: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:12464: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:13423: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:13450: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:15642: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:16293: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:17396: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:21925: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:23888: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:24544: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:25054: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:27581: 'msgid' and 'msgstr' entries do not both end with '\n'
po/ja.po:28926: 'msgid' and 'msgstr' entries do not both end with '\n'
msgfmt: found 23 fatal errors
      

Please ask the translator (identified by the Last-Translator field in the PO file), the language team (identified by the Language-Team field) or debian-i18n for a fix.