Typescript / React Redux - Ensure all actions handled in switch case

breakfastReducer.ts

type exampleReducerAction = Waffled | Pancaked | NOT_HANDLED_IN_SWITCH_CASE


function breakfastReducer( state: any, action: exampleReducerAction ): any
{
	// Note, for some reason action.type doesn't work
	switch ( action.type ) {	
		case "PancakedAction":
			return "Gimme!"

		case "WaffledAction":
			return "Moar!"

		// Because we do not handle the "NOT_HANDLED_IN_SWITCH_CASE" action
		default:
			// A vallue arrive into "ensureAllActionsHandled()"
			ensureAllActionsHandled( action )
	}
}


// But the function specifies it should get nothing by using the "never" type for it's param
function ensureAllActionsHandled( unhandledCase: never )
{
	throw new class extends Error
	{
		message = `Case ${unhandledCase} should not have been reached`
		name = `UnhandledCodeError`
	}
}

// The rest doesn't matter
interface Pancaked
{
	type: "PancakedAction"
	// ...stuff
}


interface Waffled
{
	type: "WaffledAction"
	// ...stuff
}

interface NOT_HANDLED_IN_SWITCH_CASE
{
	type: "UnhandledAction"
	// ...stuff
}