Clarify that secrets are optional

- Quit witih an error when secrets can’t be loaded
- Refactor duplicated code

Resolves #894

lib/server-secrets.js

@@ -0,0 +1,18 @@
+// Everything that cannot be checked in but is useful server-side is stored in
+// a JSON data file: private/secret.json.
+
+const fs = require('fs');
+const path = require('path');
+
+const secretsPath = path.join(__dirname, '..', 'private', 'secret.json');
+
+if (fs.existsSync(secretsPath)) {
+  try {
+    module.exports = require(secretsPath);
+  } catch(e) {
+    console.error(`Error loading secret data: ${e.message}`);
+    process.exit(1);
+  }
+} else {
+  console.warn(`No secret data found at ${secretsPath} (see lib/server-secrets.js)`);
+}

lib/suggest.js

@@ -1,13 +1,6 @@
 var nodeUrl = require('url');
 var request = require('request');
-var serverSecrets;
+var serverSecrets = require('./server-secrets');
-try {
-  // Everything that cannot be checked in but is useful server-side
-  // is stored in this JSON data.
-  serverSecrets = require('../private/secret.json');
-} catch(e) {
-  console.error('No secret data (private/secret.json, see server.js):', e);
-}
 
 // data: {url}, JSON-serializable object.
 // end: function(json), with json of the form:

server.js

@@ -29,14 +29,7 @@ var loadLogos = require('./lib/load-logos.js');
 var githubAuth = require('./lib/github-auth.js');
 var querystring = require('querystring');
 var xml2js = require('xml2js');
-var serverSecrets;
+var serverSecrets = require('./lib/server-secrets');
-try {
-  // Everything that cannot be checked in but is useful server-side
-  // is stored in this JSON data.
-  serverSecrets = require('./private/secret.json');
-} catch(e) {
-  console.error('No secret data (private/secret.json, see server.js):', e);
-}
 if (serverSecrets && serverSecrets.gh_client_id) {
   githubAuth.setRoutes(camp);
 }