fix(confighttp): do not return 200 on errors

[ReenigneArcher]

Description

• Return 400 status code on config API errors
• Remove trailing commas in API examples
• Clarify how index works when saving an app

Screenshot

Issues Fixed or Closed

• Fixes Beta API: POST /api/apps returns 200 OK on invalid input JSON #3384

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 28 lines in your changes missing coverage. Please review.

Project coverage is 11.11%. Comparing base (d1e7865) to head (f65d517).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
src/confighttp.cpp	0.00%	17 Missing and 11 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3385      +/-   ##
==========================================
- Coverage   11.12%   11.11%   -0.01%     
==========================================
  Files          99       99              
  Lines       17253    17258       +5     
  Branches     8045     8048       +3     
==========================================
- Hits         1920     1919       -1     
- Misses      12639    12796     +157     
+ Partials     2694     2543     -151     

Flag	Coverage Δ
Linux	8.36% <0.00%> (-0.01%)	⬇️
Windows	5.31% <0.00%> (-0.01%)	⬇️
macOS-13	13.59% <0.00%> (-0.03%)	⬇️
macOS-14	12.63% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/confighttp.cpp	1.86% <0.00%> (-0.40%)	⬇️

... and 22 files with indirect coverage changes

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud