Ensure exit code is non zero when command fails

[agubler]

Type: bug / feature

The following has been addressed in the PR:

• [x] There is a related issue
• [x] All code has been formatted with prettier as per the readme code style guidelines
• [x] Unit or Functional tests are included in the PR

Description:

Exit with non zero code when running a command fails.

Resolves #209

[codecov[bot]]

Codecov Report

Merging #214 into master will decrease coverage by 0.01%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #214      +/-   ##
==========================================
- Coverage   94.75%   94.74%   -0.02%     
==========================================
  Files          19       19              
  Lines         477      476       -1     
  Branches       63       62       -1     
==========================================
- Hits          452      451       -1     
  Misses         13       13              
  Partials       12       12

Impacted Files	Coverage Δ
src/registerCommands.ts	100% <100%> (ø)	:arrow_up:

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