feat(cli): better error message for ChromeDriver version mismatch

Fixes dequelabs#679.

packages/cli/src/bin/index.ts

@@ -15,6 +15,7 @@ import {
 import axeTestUrls from '../lib/axe-test-urls';
 import event from '../lib/events';
 import { startDriver } from '../lib/webdriver';
+import { error as selenium_error } from 'selenium-webdriver';
 
 const cli = async (
   args: OptionValues,
@@ -107,7 +108,28 @@ const cli = async (
     disable
   };
   try {
-    const outcome = await axeTestUrls(urls, testPageConfigParams, events);
+    let outcome;
+    try {
+      outcome = await axeTestUrls(urls, testPageConfigParams, events);
+    } catch (e) {
+      // Provide a more user-friendly error message when there's a ChromeDriver/Chrome version mismatch.
+      if (e instanceof selenium_error.SessionNotCreatedError && e.message.includes(
+        'This version of ChromeDriver only supports'
+        // This string has to match the error message printed by chromedriver, see
+        // https://chromium.googlesource.com/chromium/src/+/refs/tags/110.0.5481.194/chrome/test/chromedriver/chrome_launcher.cc#300.
+      )) {
+        console.error(error('Error: %s'), e.message);
+        console.log(`\nConsider installing a matching version of ChromeDriver with:
+
+    npm install -g chromedriver@<version>
+
+(where <version> is the desired version of Chromedriver.)
+And running \`axe\` with \`--chromedriver-path $(npm root -g)/chromedriver/bin/chromedriver\`.`)
+        process.exit(2);
+      } else {
+        throw e;
+      }
+    }
     if (silentMode) {
       process.stdout.write(JSON.stringify(outcome, null, 2));
       return;