[Themes] Theme Dev - Render asset upload errors coming from initial theme upload

[jamesmengo]

WHY are these changes introduced?

When you run theme dev, we upload files that you modify, but we also perform an initial theme upload in the background.

This PR adds results from the initial background upload to the error overlay

WHAT is this pull request doing?

Adds upload errors to the error overlay as the theme upload results are returned.

Known limitation - timing matters.
If you open the localhost window BEFORE the results are returned, the overlay won't render until your next render.

I will introduce hot reloading in a follow-up

🎥 Video uploaded on Graphite:

How to test your changes?

1. Attempt to upload a theme with invalid assets
2. Verify error messages are properly stored and displayed
3. Successfully upload assets and confirm errors are cleared
4. Test with various error scenarios to ensure proper error message handling

Measuring impact

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[jamesmengo]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [Themes] Trigger hot reload to update/render error overlay on asset upload error / fix #5211
• [Themes] Theme Dev - Render asset upload errors coming from initial theme upload #5210 👈 (View in Graphite)
• [Themes] Add error overlay for theme upload failures #5208
• [Themes] theme dev - unify asset upload error reporting #5209
• main

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[github-actions]

Differences in type declarations

We detected differences in the type declarations generated by Typescript for this branch compared to the baseline ('main' branch). Please, review them to ensure they are backward-compatible. Here are some important things to keep in mind:

• Some seemingly private modules might be re-exported through public modules.
• If the branch is behind main you might see odd diffs, rebase main into this branch.

New type declarations

We found no new type declarations in this PR

Existing type declarations

packages/cli-kit/dist/public/node/themes/types.d.ts

@@ -92,6 +92,10 @@ export interface ThemeFileSystem extends VirtualFileSystem {
     applyIgnoreFilters: <T extends {
         key: string;
     }>(files: T[]) => T[];
+    /**
+     * Stores upload errors returned when uploading files via the Asset API
+     */
+    uploadErrors: Map<Key, string[]>;
 }
 /**
  * Represents a theme on the file system.

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	75.16% (-0.01% 🔻)	8893/11832
🟡	Branches	70.28% (-0.02% 🔻)	4342/6178
🟡	Functions	75.06%	2326/3099
🟡	Lines	75.71% (-0.01% 🔻)	8408/11105

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🟢	... / ConcurrentOutput.tsx	98.36% (-1.64% 🔻)	88% (-4% 🔻)	100%	98.33% (-1.67% 🔻)

Test suite run success

2007 tests passing in 906 suites.

Report generated by 🧪jest coverage report action from 858e418