fixes issues with shutting down when vs-code extension process stops

[raleigh-g-thompson]

fixes #106

fixes cqframework/vscode-cql#95

[github-actions]

Formatting check succeeded!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 50.35%. Comparing base (3e8f452) to head (827bdcc).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #107      +/-   ##
============================================
+ Coverage     50.29%   50.35%   +0.06%     
- Complexity      278      279       +1     
============================================
  Files            46       46              
  Lines          1543     1543              
  Branches        189      189              
============================================
+ Hits            776      777       +1     
+ Misses          703      702       -1     
  Partials         64       64              

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