Avoid unnecessary file open in reader.py

[Stephen0512]

This pull request fixes a file-handling issue in reader.py. The code previously opened the file outside of a context manager, but that file handle was never used and was later reopened inside a with block. This resulted in an unnecessary file open and a potential resource leak. While Python’s garbage collector will eventually close the file once it is no longer referenced, it is generally better practice to explicitly close files or use a context manager.

This change removes the redundant open() call without changing behavior. The issue was identified during an ongoing research project.