allow for zero length partial config

[steiler]

If in the course of building a lab, you want to already point to a partial config, which is being filled later on, probably with the use of the lab itself (configuring single node via cli and adapting to other nodes ...) This will prevent the call to scrapligo and return a nil error instead of right now resulting in a panic.
Which in both cases makes the deployment fail.

[steiler]

handling #1422

[codecov]

Codecov Report

Merging #1423 (4894a9c) into main (06505dc) will increase coverage by 0.30%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1423      +/-   ##
==========================================
+ Coverage   20.32%   20.63%   +0.30%     
==========================================
  Files          58       58              
  Lines        6488     6527      +39     
==========================================
+ Hits         1319     1347      +28     
- Misses       5046     5057      +11     
  Partials      123      123              

see 2 files with indirect coverage changes