docs: function lookForExternalDependenciesRES( _def, resources, depFile ) {
    if ( !_def ) return;
    try {
      const def = convertExternalDependencyDefinition( _def );
      for ( const dep of Object.keys( def ) ) {
        if ( def[ dep ] === "" ) {
          // `res: { "bob/foo.png": "" }` is equivalent to
          // `res: { "bob/foo.png": "bob/foo.png" }`
          def[ dep ] = dep;
        }
        const
        srcDep = Project.srcOrLibPath( `mod/${dep}` ) ||
          Project.srcOrLibPath( dep );
        if ( !srcDep ) {
          Fatal.fire(
            `Unable to find dependency file "${dep}" nor "mod/${dep}"!`,
            depFile.getAbsoluteFilePath()
          );
        }
        resources[ srcDep ] = Project.wwwPath( def[ dep ] );
      }
    } catch ( ex ) {
      Fatal.fire(
        `Unable to parse RES dependencies: ${JSON.stringify(_def)}!\n${ex}`,
        depFile
      );
    }
  }