Changes
Default to placeholder flag in absence of flag alias (see also Template:Flag/core)
<span class="flagicon">[[File:{{{flag alias-{{{variant}}}|{{#if:{{{flag alias|}}}|{{{flag alias}}}|Flag placeholder.svg}}}}}|{{#if:{{{size|}}}|{{{size}}}|23x15px}}|{{{border-{{{variant}}}|{{{border|border}}}}}} |alt={{{alias}}}|link={{{alias}}}]]</span><noinclude>{{documentation}}</noinclude>