Fix nil pointer when checking for event authorizer

[mthenw]

Todos:

• Write tests
• Write documentation
• Fix linting errors
• Make sure code coverage hasn't dropped
• Provide verification commands / resources
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: NO
Is it a breaking change?: NO

[codecov]

Codecov Report

Merging #475 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #475   +/-   ##
=======================================
  Coverage   70.66%   70.66%           
=======================================
  Files          35       35           
  Lines        2175     2175           
=======================================
  Hits         1537     1537           
  Misses        574      574           
  Partials       64       64

Impacted Files	Coverage Δ
libkv/function.go	83.9% <100%> (ø)	⬆️

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