HF-131 (3/7): a consumer can tell 'no message' from 'empty message'

[marcin-kordas-hoc]

What and why

Stacked on #1762. Adds DetailedCellError.hasMessage: boolean.

DetailedCellError.message collapses two different situations into the same '': an error that
never carried a message at all (e.g. a custom function that omitted one — the public CellError
constructor keeps message optional), and an error with a deliberately empty message. A consumer
that needs to tell them apart previously couldn't. hasMessage does: true means a message was
set (even an empty string), false means none was.

Purely additive — no existing consumer of .type/.message/.value/.address needs a code
change. toString()/valueOf() are unaffected (both still return .value only).

Verified

• npx tsc --noEmit — clean
• npx eslint src/ — 0 errors
• Full private test suite reproduced against this branch's tip — no regressions beyond the same
  pre-existing branch-pinning mismatch as HF-131 (1/7): every interpreter cell error carries a message #1761/HF-131 (2/7): the origin/propagation mechanism, plus the same guarantee outside the interpreter #1762

Stack

3 of 7 — stacked on #1762. Next: feat/hf-131-origin-function.

🤖 Generated with Claude Code

---

Note

Low Risk
Additive public field on DetailedCellError with no change to existing message or value semantics; low blast radius beyond consumers that opt into hasMessage.

Overview
Adds DetailedCellError.hasMessage so callers can distinguish errors that never had a message (e.g. custom CellError without the optional message) from errors with a deliberately empty message — both still expose message as ''.

The flag is set in the DetailedCellError constructor from whether CellError.message was undefined; existing fields and toString() / valueOf() behavior are unchanged. The custom-functions guide and changelog document the distinction; test toEqualError matchers ignore hasMessage in structural compares so specs that do not assert it keep passing.

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[qunabu]

Task linked: HF-131 Verbose and actionable formula error messages

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Changelog uses issue not PR link

Low Severity

The new Unreleased changelog bullet ends with an issue link for #131 rather than a pull-request link.

 

^{Triggered by learned rule: CHANGELOG bullets need a PR link}

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	hyperformula-docs	5ed0aec	Commit Preview URL Branch Preview URL	Sep 11 2026, 05:35 AM

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Performance comparison of head (5ed0aec) vs base (749044d)

                                     testName |    base |    head | change
--------------------------------------------------------------------------
                                      Sheet A |  489.74 |  491.95 | +0.45%
                                      Sheet B |  154.64 |  161.22 | +4.26%
                                      Sheet T |  139.42 |  141.49 | +1.48%
                                Column ranges |  470.13 |  471.05 | +0.20%
                                Sorted lookup | 14084.1 | 14432.3 | +2.47%
Sheet A:  change value, add/remove row/column |    15.8 |   15.77 | -0.19%
 Sheet B: change value, add/remove row/column |  138.81 |  126.75 | -8.69%
                   Column ranges - add column |   158.4 |  148.47 | -6.27%
                Column ranges - without batch |   473.9 |  463.16 | -2.27%
                        Column ranges - batch |  116.04 |  114.67 | -1.18%

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.34%. Comparing base (749044d) to head (5ed0aec).

Additional details and impacted files

@@                               Coverage Diff                               @@
##           feat/hf-131-error-messages-outside-interpreter    #1763   +/-   ##
===============================================================================
  Coverage                                           97.34%   97.34%           
===============================================================================
  Files                                                 195      195           
  Lines                                               15825    15826    +1     
  Branches                                             3491     3491           
===============================================================================
+ Hits                                                15405    15406    +1     
  Misses                                                412      412           
  Partials                                                8        8           

Files with missing lines	Coverage Δ
src/CellValue.ts	80.00% <100.00%> (+2.22%)	⬆️

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