fix(form-core): Fix setBy/getBy not handling arrays properly

[LeCarbonator]

Closes #1488

During parsing of the field name, multi-dimensional arrays (or names starting with an array access) were wrongly parsed in functions using makePathArray internally.

The side effects of this are listed in the linked issue, but to summarize, it wrongly interpreted array access as an object key, and that apparently lead to JavaScript silently converting the array into an object (classic ...)

The reason were mostly the regular expressions used to parse the field name, so test cases have been added and the function has been refactored.

Before

makePathArray('field[0][1].value') 
// == ['field', 0, '1', 'value']

With PR

makePathArray('field[0][1].value') 
// == ['field', 0, 1, 'value']

There is now a lookahead used to avoid mismatches with subsequent numbers. Benchmarks didn't show a significant drop in performance, but let me know if you notice something suspicious.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit a4d992a.

Command	Status	Duration	Result
nx affected --targets=test:sherif,test:knip,tes...	✅ Succeeded	1m 27s	View ↗
nx run-many --target=build --exclude=examples/**	✅ Succeeded	21s	View ↗

---

☁️ Nx Cloud last updated this comment at 2025-05-20 05:34:39 UTC

[pkg-pr-new]

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commit: a4d992a

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.13%. Comparing base (f13c4ec) to head (a4d992a).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1517   +/-   ##
=======================================
  Coverage   89.13%   89.13%           
=======================================
  Files          31       31           
  Lines        1417     1417           
  Branches      362      362           
=======================================
  Hits         1263     1263           
  Misses        137      137           
  Partials       17       17           

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[bompi88]

LGTM 🚀