fix(cli): exit with error status if an app is not installed

BREAKING CHANGE:
The following scenarios will display an error and exit with a status
code of 1, where previously they would display a warning:

+ Not using `--no-imageoptim` when ImageOptim.app is not installed.
+ Using `--imagealpha` when ImageAlpha.app is not installed.
+ Using `--jpegmini` when JPEGmini.app is not installed.

Closes #180

src/log.ts

@@ -16,6 +16,11 @@ export const bug = (err: Error): void => {
   process.exit(1);
 };
 
+export const panic = (value: string): void => {
+  console.log(color.red('! %s'), value);
+  process.exit(1);
+};
+
 export const result = (
   label: string = 'TOTAL',
   prettySizeBefore: string,

src/run-imagealpha.ts

@@ -2,7 +2,7 @@ import { pathExists } from 'fs-extra';
 import { AppRunner, IOptions } from '.';
 import { IMAGEALPHA, IMAGEALPHA_URL, PNGQUANT_BIN_PATH } from './constants';
 import { isSupported } from './is-supported';
-import { info, verbose, warning } from './log';
+import { info, panic, verbose } from './log';
 import { pngquant } from './pngquant';
 
 export const runImageAlpha: AppRunner = async (options: IOptions) => {
@@ -11,7 +11,7 @@ export const runImageAlpha: AppRunner = async (options: IOptions) => {
     .map((file) => file.tmp)
     .filter(isSupported(IMAGEALPHA.supports));
   if (!(await pathExists(PNGQUANT_BIN_PATH))) {
-    return warning(`ImageAlpha.app is not installed (${IMAGEALPHA_URL})`);
+    return panic(`ImageAlpha.app is not installed (${IMAGEALPHA_URL})`);
   }
   await pngquant(pngFilePaths, options);
   verbose(`${IMAGEALPHA.name} has finished`);

src/run-imageoptim.ts

@@ -2,12 +2,12 @@ import * as execa from 'execa';
 import { pathExists } from 'fs-extra';
 import { AppRunner } from '.';
 import { IMAGEOPTIM, IMAGEOPTIM_BIN_PATH, IMAGEOPTIM_URL } from './constants';
-import { info, verbose, warning } from './log';
+import { info, panic, verbose } from './log';
 
 export const runImageOptim: AppRunner = async (options) => {
   info(`Running ${IMAGEOPTIM.name}...`);
   if (!(await pathExists(IMAGEOPTIM_BIN_PATH))) {
-    return warning(`ImageOptim.app is not installed (${IMAGEOPTIM_URL})`);
+    return panic(`ImageOptim.app is not installed (${IMAGEOPTIM_URL})`);
   }
   await execa(IMAGEOPTIM_BIN_PATH, [options.tmpDir]);
   verbose(`${IMAGEOPTIM.name} has finished`);

src/run-jpegmini.ts

@@ -5,8 +5,8 @@ import {
   runJpegMini as startJpegMini,
   supportsAssistiveDevices
 } from './applescript';
-import { ASSISTIVE_DEVICES_URL, HOMEPAGE_URL, JPEG_MINI_URL } from './constants';
-import { info, verbose, warning } from './log';
+import { ASSISTIVE_DEVICES_URL, JPEG_MINI_URL } from './constants';
+import { info, panic, verbose } from './log';
 
 export const runJpegMini: AppRunner = async (options) => {
   verbose('Locating JPEGmini installation');
@@ -18,11 +18,11 @@ export const runJpegMini: AppRunner = async (options) => {
   const [app, canAutomate] = await Promise.all([jpegMini, assistiveDeviceSupport]);
 
   if (!app) {
-    return warning(`JPEGmini is not installed (${JPEG_MINI_URL})`);
+    return panic(`JPEGmini is not installed (${JPEG_MINI_URL})`);
   }
 
   if (!canAutomate) {
-    return warning(`Support for assistive devices needed, see ${ASSISTIVE_DEVICES_URL}`);
+    return panic(`Support for assistive devices needed, see ${ASSISTIVE_DEVICES_URL}`);
   }
 
   info(`Running ${app.name}...`);