fix: include payable amount when zero and respect generateOnZero flag

[SimonLoir]

This commit addresses an issue where zero payable amounts were not included correctly and ensures other zero amounts are omitted when the generateOnZero flag is set to false.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: ff2a58ed-0dce-44ec-a8bd-4774b5049c7f

📥 Commits

Reviewing files that changed from the base of the PR and between 95ccb1d and cbb712b.

📒 Files selected for processing (1)

• package.json

📝 Walkthrough

Walkthrough

The PR updates monetary XML generation in Peppol UBL documents to correctly emit PayableAmount when its value is 0, while preserving the existing behavior of omitting null or undefined amounts. A new type-guard helper distinguishes these cases, and tests validate the behavior for both invoices and credit notes.

Changes

PayableAmount zero-value handling

Layer / File(s)	Summary
Type guard and amount generation logic src/helpers/isNullish.ts, src/builder/DocumentBuilder.ts	isNullish type guard is introduced to check for null or undefined. DocumentBuilder imports it, extends __buildAmount with an optional generateOnZero parameter to allow zero-value emission, and updates __buildMonetaryTotal to pass the flag when building PayableAmount.
Test validation for invoice and credit note tests/builder-invoice.test.ts, tests/builder-creditnote.test.ts	Two test cases per document type validate that PayableAmount is always included with 0.00 when zero, and that other zero-valued monetary fields are omitted when generateOnZero is false.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• PixelDrive/peppol-toolkit#10: Both PRs modify __buildMonetaryTotal and __buildAmount logic in DocumentBuilder to change how cbc:PayableAmount is emitted for zero values.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main fix: ensuring payable amounts are included when zero while respecting the generateOnZero flag for other amounts.
Description check	✅ Passed	The description directly relates to the changeset by explaining the fix for zero payable amounts and the generateOnZero flag behavior.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix-zero-payable-amount

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/helpers/isNullish.ts`:
- Around line 1-2: The isNullish function currently types its parameter as any;
change the parameter type to unknown to improve type safety while preserving the
type guard signature (export const isNullish = (value: unknown): value is null |
undefined => ...). Update the parameter type in the isNullish function
definition and keep the existing null/undefined checks so the runtime behavior
and the type predicate remain unchanged.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 704a6b34-3541-4aa5-8ba9-18960f0be3ce

📥 Commits

Reviewing files that changed from the base of the PR and between 9ae7ba1 and 95ccb1d.

📒 Files selected for processing (4)

• src/builder/DocumentBuilder.ts
• src/helpers/isNullish.ts
• tests/builder-creditnote.test.ts
• tests/builder-invoice.test.ts

[codacy-production]

Not up to standards ⛔

🔴 Issues 1 high

Alerts:
⚠ 1 issue (≤ 0 issues of at least minor severity)

Results:
1 new issue

Category	Results
BestPractice	1 high

View in Codacy

🟢 Metrics 0 complexity · 0 duplication

Metric	Results
Complexity	0
Duplication	0

View in Codacy

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