Error Types

Prose exports three error classes, all extending Error.

ValidationError

Thrown by .validate() steps for input validation failures.

Constructor

new ValidationError(message: string, issues?: ValidationIssue[])

Static helpers

ValidationError.single(field: string, message: string): ValidationError
ValidationError.multiple(issues: ValidationIssue[]): ValidationError

Properties

Property	Type	Description
message	string	Error message
issues	ValidationIssue[]	Array of { field, message } objects

Methods

• .toJSON() — Returns a serializable representation with message and issues

Example

// Single field
throw ValidationError.single('email', 'Invalid email');

// Multiple fields
throw new ValidationError('Validation failed', [
  { field: 'email', message: 'Required' },
  { field: 'age', message: 'Must be at least 18' },
]);

FlowExecutionError

Thrown when a step fails during execution. Wraps the original error.

Constructor

new FlowExecutionError(flowName: string, stepName: string, originalError: Error)

Properties

Property	Type	Description
flowName	string	Name of the flow
stepName	string	Name of the step that failed
originalError	Error	The actual error thrown by the step

TimeoutError

Thrown when a flow or step exceeds its configured timeout.

Properties

Property	Type	Description
flowName	string	Name of the flow
stepName	string | undefined	Step name (undefined for flow-level timeout)
timeoutMs	number	The timeout value that was exceeded