Show error only when in verbose mode

[NejcZdovc]

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.

Resolves #12311

Auditors:

Test Plan:

• clean profile
• start browser
• there shouldn't be any 404 error related to promotions

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[mrose17]

LGTM.

[codecov-io]

Codecov Report

Merging #12312 into master will increase coverage by 0.53%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #12312      +/-   ##
==========================================
+ Coverage   55.29%   55.82%   +0.53%     
==========================================
  Files         276      277       +1     
  Lines       26740    27526     +786     
  Branches     4310     4711     +401     
==========================================
+ Hits        14786    15367     +581     
- Misses      11954    12159     +205

Flag	Coverage Δ
#unittest	55.82% <100%> (+0.53%)	⬆️

Impacted Files	Coverage Δ
app/browser/api/ledger.js	50.72% <100%> (+0.12%)	⬆️
app/renderer/components/common/switchControl.js	82.66% <0%> (-2.7%)	⬇️
js/about/preferences.js	44.72% <0%> (-0.4%)	⬇️
js/constants/windowConstants.js	100% <0%> (ø)	⬆️
app/common/constants/settingsEnums.js	100% <0%> (ø)	⬆️
app/renderer/components/styles/global.js	100% <0%> (ø)	⬆️
app/browser/activeTabHistory.js	90.32% <0%> (ø)
js/actions/windowActions.js	5.02% <0%> (+0.16%)	⬆️
app/renderer/components/common/messageBox.js	88.34% <0%> (+0.59%)	⬆️
... and 13 more

[bsclifton]

master 66e64db
0.21.x 04aa5f2

[NejcZdovc]

0.21 twitch b1f0403