fix: handle with read the empty file

[JiChenSSG]

#4217

Handle with empty file read and the condition that first is the same as last line and with out line break.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.12%. Comparing base (8690859) to head (cdc9f5a).
Report is 91 commits behind head on master.

Additional details and impacted files

Files	Coverage Δ
core/filex/file.go	89.47% <100.00%> (+4.72%)	⬆️

... and 254 files with indirect coverage changes