stderr & stdout order is puzzled

command.js

        this.processCmd = options.isCustom ?
          `npm run ${ script.name }` :
          script.command;

        this.$set( 'process', this.exec(
          this.processCmd,
          {
            cwd : options.cwd
          }
        ) );

        this.process.stdout.on( 'data', this.handleData );
        this.process.stderr.on( 'data', this.handleData );
        
        // 
        // it seams when large data coming from stdout
        // and tiny data coming from stderr 
        // that stderr somehow gets called first
        //
        // -> puzzled order in data display happening in handleData
        
        // e.g. npm ls
        // -> running `npm ls` from the terminal shows a big chunk of stdout ( the list ) and 
        //    errors at the end
        
        // that leads to my assumption that this is the correct order
        
        // -> running `npm ls` from within node a child process I got
        //    chunks of stdout and stderr right in the middle somehwhere
        
        // *****************************************
        // is this a thing? large data ( enourmous strings ) delaying the handler call?