encrypt.go: Fix panic on reading empty file

[mr-karan]

Fixes a panic crash when a file is loaded without any contents.
Adds a new error FileContentsEmpty in codes.go.

Fixes #483

[codecov-io]

Codecov Report

Merging #485 (66c9248) into develop (d61906a) will decrease coverage by 0.11%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #485      +/-   ##
===========================================
- Coverage    36.38%   36.26%   -0.12%     
===========================================
  Files           20       20              
  Lines         2718     2760      +42     
===========================================
+ Hits           989     1001      +12     
- Misses        1640     1666      +26     
- Partials        89       93       +4     

Impacted Files	Coverage Δ
config/config.go	64.46% <0.00%> (-12.76%)	⬇️
stores/flatten.go	87.28% <0.00%> (-4.24%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d61906a...66c9248. Read the comment docs.

[autrilla]

Thanks for the patch! I don't think this will catch the case where a user runs sops file.yaml, and then empties the file

[ajvb]

Thanks @mr-karan! imo we should also make sure to add a regression test with the patch.

[mr-karan]

@autrilla Um I am not sure if I got you. When the user runs sops -e file.yaml the file contents are loaded in memory, so it won't really matter what the user does to the file after running this command.
Did you mean something else?

@ajvb On it 👍

[autrilla]

@autrilla Um I am not sure if I got you. When the user runs sops -e file.yaml the file contents are loaded in memory, so it won't really matter what the user does to the file after running this command.
Did you mean something else?

It doesn't panic, but creating a new file with sops new_file.yaml, emptying the contents, and saving it, creates an empty file with no sops section. It should probably just error, since it doesn't make sense. And it's the same if you edit an existing file with sops existing_file.yaml and empty the contents. I think we should emit the same error in those cases.

[jvehent]

@mr-karan Are you still making changes to this PR or should we close it?