fix: improve validation error messages

[mag123c]

Improves validation error messages to include event names and field paths, making debugging significantly easier.
Fixed #42

Changes

Before:

Error: Validation failed

After:

Validation failed: "user:created"
  - body.email: Invalid email: Received "not-an-email"
  - body.age: Invalid value: Expected >=13 but received 10

Added formatStandardSchemaIssues helper function in src/standard.ts. Formats Standard Schema issues into readable error messages with

• Event name (when available)
• Field paths in dot notation
• Original validation messages from the schema library

Test Approach

Added a single test that validates the core improvement: event name inclusion in error messages.

The test intentionally avoids checking implementation details (specific field names, exact error messages, formatting) and only verifies

.toThrow('Validation failed: "user:created"');

Question: Is this the right level of test coverage? I kept it minimal to

• Avoid coupling tests to validation library message formats (which may change)
• Follow the existing test convention (simple string matching with .toThrow())
• Focus on the key feature: event names in error messages

Notes

Implementation inspired by Zod's prettifyError you mentioned but adapted for Standard Schema's simpler issue format

[tonyfromundefined]

@mag123c Can you add changeset? You can easily write a version and detailed description with $ yarn changeset . After creating the file, just commit and push it.

[tonyfromundefined]

I think you should submit it as a patch version.

[mag123c]

@tonyfromundefined added changeset 😃