fix(*): throw Error objects to help with debugging

lib/auth.js

@@ -7,26 +7,21 @@ import { clearCachedConfig, encryptValue, getMergedConfig, getNcurcPath } from '
 
 export default lazy(auth);
 
-function errorExit(message) {
-  process.stderr.write(`${message}\n`);
-  process.exit(1);
-}
-
 function check(username, token, format = /^[A-Za-z0-9_]+$/) {
   if (typeof username !== 'string') {
-    errorExit(`username must be a string, received ${typeof username}`);
+    throw new Error(`username must be a string, received ${typeof username}`);
   }
   if (!/^[a-zA-Z0-9-]+$/.test(username)) {
-    errorExit(
+    throw new Error(
       'username may only contain alphanumeric characters or hyphens, ' +
       `received ${username}`
     );
   }
   if (typeof token !== 'string') {
-    errorExit(`token must be a string, received ${typeof token}`);
+    throw new Error(`token must be a string, received ${typeof token}`);
   }
   if (!format.test(token)) {
-    errorExit(`token is misformatted: ${token}`);
+    throw new Error(`token is misformatted: ${token}`);
   }
 }
 
@@ -51,7 +46,7 @@ async function tryCreateGitHubToken(githubAuth) {
       noDeviceFlow: true
     });
   } catch (e) {
-    errorExit(`Could not get token: ${e.message}`);
+    throw new Error(`Could not get token: ${e.message}`, { cause: e });
   }
   return credentials;
 }
@@ -93,7 +88,7 @@ async function auth(
     get jenkins() {
       const { username, jenkins_token } = getMergedConfig();
       if (!username || !jenkins_token) {
-        errorExit(
+        throw new Error(
           'Get your Jenkins API token in https://ci.nodejs.org/me/security ' +
           'and run the following command to add it to your ncu config: ' +
           'ncu-config --global set -x jenkins_token'