From b256d2f8d98973df93b397bf2ec8b1d84688cc8f Mon Sep 17 00:00:00 2001
From: Frank Li <frankli1@fb.com>
Date: Wed, 9 Aug 2017 15:43:30 -0700
Subject: [PATCH] Initial changes to error messages

---
 lib/build-files.js           | 14 +++++++++++++-
 lib/core/nav/HeaderNav.js    |  6 ++++++
 lib/server/readCategories.js |  2 +-
 lib/server/readMetadata.js   |  9 +++++++--
 lib/server/server.js         |  5 ++++-
 lib/start-server.js          | 14 +++++++++++++-
 package.json                 |  1 +
 7 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/lib/build-files.js b/lib/build-files.js
index e26f4701a4..fdd692161f 100755
--- a/lib/build-files.js
+++ b/lib/build-files.js
@@ -11,10 +11,22 @@
 
 require("babel-register")({
   babelrc: false,
-  only: [__dirname, process.cwd() + "/core"],  
+  only: [__dirname, process.cwd() + "/core"],
   plugins: [require("./server/translate-plugin.js")],
   presets: ["react", "latest"]
 });
 
+// initial check that required files are present
+const chalk = require("chalk");
+const fs = require("fs");
+const CWD = process.cwd();
+
+if (!fs.existsSync(CWD + "/siteConfig.js")) {
+  console.error(
+    chalk.red("Error: No siteConfig.js file found in website folder!")
+  );
+  process.exit(1);
+}
+
 const generate = require("./server/generate.js");
 generate();
diff --git a/lib/core/nav/HeaderNav.js b/lib/core/nav/HeaderNav.js
index cbdf609c78..94807165d2 100644
--- a/lib/core/nav/HeaderNav.js
+++ b/lib/core/nav/HeaderNav.js
@@ -128,6 +128,12 @@ class HeaderNav extends React.Component {
           "-" +
           link.doc;
       }
+      if (!Metadata[id]) {
+        throw new Error(
+          "A headerLink is specified with a document that does not exist. No document exists with id: " +
+            link.doc
+        );
+      }
       href = this.props.config.baseUrl + Metadata[id].permalink;
     } else if (link.page) {
       if (fs.existsSync(CWD + "/pages/en/" + link.page + ".js")) {
diff --git a/lib/server/readCategories.js b/lib/server/readCategories.js
index c90310992e..8b19614679 100644
--- a/lib/server/readCategories.js
+++ b/lib/server/readCategories.js
@@ -56,7 +56,7 @@ function readCategories(sidebar) {
       if (metadata.next) {
         if (!articles[metadata.next]) {
           throw new Error(
-            "`next: " + metadata.next + "` in " + metadata.id + " doesn't exist"
+            "Improper sidebars.json file. Make sure that documents with the ids specified in sidebars.json exist and that no ids are repeated."
           );
         }
         previous[articles[metadata.next].id] = metadata.id;
diff --git a/lib/server/readMetadata.js b/lib/server/readMetadata.js
index 90f7463af9..9ba22a0c36 100644
--- a/lib/server/readMetadata.js
+++ b/lib/server/readMetadata.js
@@ -32,7 +32,12 @@ if (fs.existsSync(CWD + "/languages.js")) {
 }
 
 function readSidebar() {
-  let allSidebars = require(CWD + "/sidebars.json");
+  let allSidebars;
+  if (fs.existsSync(CWD + "/sidebars.json")) {
+    allSidebars = require(CWD + "/sidebars.json");
+  } else {
+    allSidebars = {};
+  }
   Object.assign(allSidebars, versionFallback.sidebarData());
 
   const order = {};
@@ -155,7 +160,7 @@ function processMetadata(file) {
       metadata.previous = language + "-" + order[id].previous;
     }
   }
-  
+
   return { metadata, rawContent: rawContent };
 }
 
diff --git a/lib/server/server.js b/lib/server/server.js
index 516e86f7bc..712ba2baac 100644
--- a/lib/server/server.js
+++ b/lib/server/server.js
@@ -157,6 +157,10 @@ function execute(port) {
     });
 
     const metadata = Metadata[links[url]];
+    if (!metadata) {
+      next();
+      return;
+    }
     const language = metadata.language;
 
     let file;
@@ -438,7 +442,6 @@ function execute(port) {
     res.send(cssContent);
   });
 
-  /* serve static content first from user folder then from docusaurus */
   app.use(
     siteConfig.baseUrl + "docs/assets/",
     express.static(CWD + "/../docs/assets")
diff --git a/lib/start-server.js b/lib/start-server.js
index 7183b577cb..49163d46e0 100755
--- a/lib/start-server.js
+++ b/lib/start-server.js
@@ -11,11 +11,23 @@
 
 require("babel-register")({
   babelrc: false,
-  only: [__dirname, process.cwd() + "/core"],  
+  only: [__dirname, process.cwd() + "/core"],
   plugins: [require("./server/translate-plugin.js")],
   presets: ["react", "latest"]
 });
 
+// initial check that required files are present
+const chalk = require("chalk");
+const fs = require("fs");
+const CWD = process.cwd();
+
+if (!fs.existsSync(CWD + "/siteConfig.js")) {
+  console.error(
+    chalk.red("Error: No siteConfig.js file found in website folder!")
+  );
+  process.exit(1);
+}
+
 const program = require("commander");
 
 program.option("--port <number>", "Specify port number").parse(process.argv);
diff --git a/package.json b/package.json
index 4fb48e9e29..906b8cfd24 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,7 @@
     "babel-register": "^6.24.1",
     "babel-traverse": "^6.25.0",
     "babylon": "^6.17.4",
+    "chalk": "^2.1.0",
     "classnames": "^2.2.5",
     "commander": "^2.11.0",
     "diff": "^3.3.0",