UIP-3039 Get rid of dart2js compiler warnings

[aaronlademann-wf]

Ultimate problem:

A few pieces of our code was causing noisy dart2js compiler output for our consumers.

How it was fixed:

Address those items.

Testing suggestions:

Passing CI build

Potential areas of regression:

None expected.

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FYA: @Workiva/app-frameworks

[aviary2-wf]

Raven

Number of Findings: 0

Magpie

Number of findings: 0

[codecov-io]

Codecov Report

Merging #137 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #137   +/-   ##
=======================================
  Coverage   94.54%   94.54%           
=======================================
  Files          33       33           
  Lines        1591     1591           
=======================================
  Hits         1504     1504           
  Misses         87       87

[jayudey-wf]

QA +1

• Testing instruction
• Dev +1's
• Dev/QA +10 with detail of what was tested
  • passing CI
• Security review (if required)
• Unit tests created/updated (n/a dart2js updates)
• All unit tests pass
• Rosie has run and reports properly the release the ticket will be included in
• Areas of regression noted

Merging into master.

[jayudey-wf]

@Workiva/release-management-pp