docs: function lookForExternalDependenciesJS( _def, javascriptSources ) {
    if ( !_def ) return;
    try {
      const def = convertExternalDependencyDefinition( _def );
      Object.keys( def ).forEach( function ( js ) {
        const
        filename = `mod/${js}`,
        src = new Source( Project, filename ),
        code = src.read();
        pushUnique( javascriptSources, code );
      } );
    } catch ( ex ) {
      Fatal.fire(
        `Unable to parse JS dependencies: ${JSON.stringify(_def)}!\n${ex}`,
        javascriptSources
      );
    }
  }