Ensure ConsoleErrorPage handler does not count towards backend…

[seanlip]

Explanation

Per @lilithxxx's comment here, this PR fixes the codebase coverage to be 100% again.

Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• The PR explanation includes the words "Fixes #bugnum: ..." (or "Fixes part of #bugnum" if the PR only partially fixes an issue).
• The linter/Karma presubmit checks have passed.
• The PR is made from a branch that's not called "develop".
• The PR has an appropriate "PROJECT: ..." label (Please add this label for the first-pass review of the PR).
• The PR has an appropriate "CHANGELOG: ..." label (If you are unsure of which label to add, ask the reviewers for guidance).
• The PR follows the style guide.
• The PR addresses the points mentioned in the codeowner checks for the files/folders changed. (See the codeowner's wiki page.)
• The PR is assigned to an appropriate reviewer.

[oppiabot]

Assigning @kevinlee12 for the first-pass review of this pull request. Thanks!

[lilithxxx]

LGTM

[codecov]

Codecov Report

Merging #7655 into develop will increase coverage by <.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #7655      +/-   ##
===========================================
+ Coverage    83.67%   83.67%   +<.01%     
===========================================
  Files         1106     1106              
  Lines        64402    64401       -1     
  Branches      3654     3654              
===========================================
  Hits         53882    53882              
+ Misses        9336     9335       -1     
  Partials      1184     1184

Flag	Coverage Δ
#backend	100% <ø> (ø)	⬆️
#frontend	73.28% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
core/controllers/pages.py	100% <ø> (+3.85%)	⬆️

[vojtechjelinek]

LGTM!