问ruby 在原文本文件中将每一行前面的部分进行删除，如果当前行没有内容写到test.txt文件中？

以下内容中，”数字<##>” 部分需要删除掉；

0<##>A Flight Determination of the Moments of the YG-1B Tapered Blade Rotor about the Hub Trunnions

1<##>At the request of the Materiel Division, Wright Field, the National ….

2<##>Results of Landing Tests of Kellett YG-1 Autogiro (A. C. R. 35-278)

3<##>Flight tests were made with a Kellett YG-1 autogiro to determine the relationship between ….

4<##>Blade Motion and Bouncing Tests of KD-1 Autogiro

。。。。

如果当前行在删除”数字<##>” 部分后没有其他内容，就将当前行存放到error-1.txt文件中