fix/undefined activity

[allanhvam]

No description provided.

[Copilot]

Pull Request Overview

This PR adds error handling for undefined activities and services in workflow execution, addressing cases where proxy objects are created with invalid targets or where activity functions don't exist.

• Added validation to prevent proxy creation with non-object targets
• Added runtime checks for undefined activity functions with descriptive error messages
• Included comprehensive test coverage for both undefined service and undefined function scenarios

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

File	Description
src/proxy/proxyActivities.ts	Added validation for undefined activities and function existence checks
src/tests/workflow-invalid.test.ts	New test file covering undefined service and function error scenarios
src/tests/workflow-throws.test.ts	Removed debug console.dir statement from existing test
package.json	Version bump from 0.5.3 to 0.5.4

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[Copilot]

The error message uses typeof activities which will always be 'object' for objects, making the message unclear. Consider using activities.constructor.name or a more descriptive identifier.

Suggested change

	throw new Error(`simple-workflows: ${typeof activities}.${activityType} is not a function`);
	throw new Error(`simple-workflows: ${(activities.constructor?.name ?? typeof activities)}.${activityType} is not a function`);