IErrors fail methods will now return 'never' so tsc can detect dead code

declarations.d.ts

@@ -537,9 +537,9 @@ interface IOpener {
 }
 
 interface IErrors {
-	fail(formatStr: string, ...args: any[]): void;
-	fail(opts: { formatStr?: string; errorCode?: number; suppressCommandHelp?: boolean }, ...args: any[]): void;
-	failWithoutHelp(message: string, ...args: any[]): void;
+	fail(formatStr: string, ...args: any[]): never;
+	fail(opts: { formatStr?: string; errorCode?: number; suppressCommandHelp?: boolean }, ...args: any[]): never;
+	failWithoutHelp(message: string, ...args: any[]): never;
 	beginCommand(action: () => Promise<boolean>, printCommandHelp: () => Promise<boolean>): Promise<boolean>;
 	verifyHeap(message: string): void;
 	printCallStack: boolean;

errors.ts

@@ -122,7 +122,7 @@ export class Errors implements IErrors {
 
 	public printCallStack: boolean = false;
 
-	public fail(optsOrFormatStr: any, ...args: any[]): void {
+	public fail(optsOrFormatStr: any, ...args: any[]): never {
 		const argsArray = args || [];
 
 		let opts = optsOrFormatStr;
@@ -146,9 +146,9 @@ export class Errors implements IErrors {
 		throw exception;
 	}
 
-	public failWithoutHelp(message: string, ...args: any[]): void {
+	public failWithoutHelp(message: string, ...args: any[]): never {
 		args.unshift(message);
-		this.fail({ formatStr: util.format.apply(null, args), suppressCommandHelp: true });
+		return this.fail({ formatStr: util.format.apply(null, args), suppressCommandHelp: true });
 	}
 
 	public async beginCommand(action: () => Promise<boolean>, printCommandHelp: () => Promise<boolean>): Promise<boolean> {

test/unit-tests/common-options.ts

@@ -38,12 +38,12 @@ describe("common options", () => {
 		testInjector = createTestInjector();
 
 		const errors = new Errors(testInjector);
-		errors.failWithoutHelp = (message: string, ...args: any[]): void => {
+		errors.failWithoutHelp = <any>((message: string, ...args: any[]): void => {
 			isExecutionStopped = true;
-		};
-		errors.fail = (message: string, ...args: any[]): void => {
+		});
+		errors.fail = <any>((message: string, ...args: any[]): void => {
 			isExecutionStopped = true;
-		};
+		});
 
 		testInjector.register("errors", errors);
 		isExecutionStopped = false;

test/unit-tests/stubs.ts

@@ -43,14 +43,14 @@ export class CommonLoggerStub implements ILogger {
 export class ErrorsStub implements IErrors {
 	printCallStack: boolean = false;
 
-	fail(formatStr: string, ...args: any[]): void;
-	fail(opts: { formatStr?: string; errorCode?: number; suppressCommandHelp?: boolean }, ...args: any[]): void;
+	fail(formatStr: string, ...args: any[]): never;
+	fail(opts: { formatStr?: string; errorCode?: number; suppressCommandHelp?: boolean }, ...args: any[]): never;
 
-	fail(...args: any[]) {
+	fail(...args: any[]): never {
 		throw new Error(util.format.apply(null, args));
 	}
 
-	failWithoutHelp(message: string, ...args: any[]): void {
+	failWithoutHelp(message: string, ...args: any[]): never {
 		throw new Error(message);
 	}