[v5] Add missing page icon types and other misc fixes

[ksinder]

This PR adds a few small fixes to our planned upcoming release of v5 of the SDK:

• (Re-)add the mistakenly removed ExternalPageIconRequest and CustomEmojiPageIconRequest types under PageIconRequest
• Add first-class support of the new optional additional_data field in public API error responses to APIResponseError
• Commit some missing files for examples/ builds, e.g. examples/generate-random-data/tsconfig.json, that I forgot to commit up in [v5] Sync API shape changes for data_source parents and search filter #602

[Copilot]

Pull Request Overview

This PR adds missing page icon types and implements error handling improvements for the v5 SDK release. The changes focus on restoring previously removed page icon types and enhancing API error responses with additional metadata.

• Re-adds ExternalPageIconRequest and CustomEmojiPageIconRequest types that were mistakenly removed
• Implements support for the new additional_data field in API error responses
• Commits missing build configuration files for examples

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/api-endpoints.ts	Restores missing page icon types and adds new type definitions
src/errors.ts	Adds support for additional_data field in API error handling
test/Client.test.ts	Adds test coverage for the new error response format
examples/generate-random-data/tsconfig.json	Adds missing TypeScript configuration file
examples/database-email-update/tsconfig.tsbuildinfo	Adds TypeScript build info file

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[Copilot]

Using a type assertion as AdditionalData | undefined bypasses type checking and could lead to runtime errors if the API returns additional_data with unexpected structure. Consider implementing proper validation or using a more permissive type definition.

Suggested change

	additional_data: parsed["additional_data"] as AdditionalData | undefined,
	additional_data: isAdditionalData(parsed["additional_data"]) ? parsed["additional_data"] : undefined,

[ksinder]

I can't really think of a good way to do a runtime check of the keys of an object being strings in JS :/ I feel like this is a necessary evil here (at the boundary of the web API call interface) and we kind of have to do some level of casting or ugly code and I chose the casting 😅)

[nsparikh]

yay!