Fix multi-column Row NaN (default cells to column count) + border wid…

[ivoIturrieta]

…th px unit

Two type-checks-but-renders-broken footguns found by cold-start agent testing:

• A multi-column with no layout/cells defaulted cells to [1] regardless of column count, so the 2nd/3rd had no cell and rendered width="NaN". Default to one equal cell PER child, matching renderToJson. (Also makes a layout accidentally placed on harmless — the Row no longer NaNs.)

• A number border width (borderTopWidth: 1) rendered border-top: 1 solid (invalid CSS the browser drops), even though BorderInput + its JSDoc accept a number. Normalize border *Width fields (number / unit-less numeric string → px) in the mapper, for both nested border objects and gathered flat side props.

+6 tests (shared mapper normalization + react render-level for both).

Summary

What does this PR do? Keep it brief.

Changes

Test Plan

• pnpm build passes
• pnpm test passes
• Tested in Storybook (if UI change)
• Added/updated tests for new behavior

Notes

Any additional context for reviewers.

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📖 Storybook Preview: https://unlayer.github.io/elements/pr/35/

[Copilot]

Pull request overview

This PR fixes two render-time “type-checks-but-breaks” cases in the React email renderer by (1) defaulting <Row> cell layouts to match the number of <Column> children (preventing NaN widths) and (2) normalizing border width values so unitless widths render as valid CSS (Npx).

Changes:

• Default <Row> cells to one equal cell per direct <Column> child when neither layout nor cells is provided.
• Normalize border*Width values (number / unitless numeric string → "Npx") inside the semantic-props mapper, including gathered flat side props.
• Add regression tests covering both behaviors at the shared mapper level and at the React render-to-HTML/JSON level.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
packages/shared/src/utils/semantic-props.ts	Adds border width normalization in mapSemanticProps after border-side prop gathering.
packages/shared/src/utils/semantic-props.test.ts	Adds unit normalization tests for nested and gathered border width props.
packages/react/src/dx-footguns.test.tsx	Adds regression tests ensuring no NaN widths for multi-column Rows and px units for border widths.
packages/react/src/components/Row.tsx	Updates default cells behavior to match <Column> child count when layout/cells are omitted.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.