output: always return data in String even with error

[bobheadxi]

Previously, if the command error'd no output would be returned.

[codecov-commenter]

Codecov Report

Merging #38 (7a44ebb) into main (2ddd06d) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##             main      #38   +/-   ##
=======================================
  Coverage   73.78%   73.78%           
=======================================
  Files          10       10           
  Lines         309      309           
=======================================
  Hits          228      228           
  Misses         64       64           
  Partials       17       17           

Impacted Files	Coverage Δ
output.go	90.26% <0.00%> (ø)

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