From 192e3b23dd79cd0072d8e31de60ca520f8c4e49d Mon Sep 17 00:00:00 2001
From: Aleksander Nowodzinski <a.nowodzinski@cksource.com>
Date: Fri, 6 Jul 2018 17:21:48 +0200
Subject: [PATCH 1/3] Imported the version.js module from ckeditor5.

---
 src/version.js | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 src/version.js

diff --git a/src/version.js b/src/version.js
new file mode 100644
index 0000000..f3a09ea
--- /dev/null
+++ b/src/version.js
@@ -0,0 +1,39 @@
+/**
+ * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+/**
+ * @module utils/version
+ */
+
+/* global window, global */
+
+import log from './log';
+import { version } from '../package.json';
+
+const windowOrGlobal = typeof window === 'object' ? window : global;
+
+if ( windowOrGlobal.CKEDITOR_VERSION ) {
+	/**
+	 * This error is thrown when the base {@link module:core/editor/editor~Editor `Editor`}
+	 * class has been loaded twice (or more), a result of either:
+	 *
+	 * * the build containing two (or more) different versions of the {@link module:core/editor/editor~Editor `Editor`}
+	 * class – make sure **all** packages in your {@glink builds/index build} which have
+	 * `@ckeditor/ckeditor5-core` in their `package.json` [dependencies](https://docs.npmjs.com/files/package.json#dependencies)
+	 * use the same version of the package,
+	 * * two (or more) `ckeditor.js` builds loaded in the web page next to one another – check your web page for duplicated
+	 * `<script>` elements or make sure your page builder/bundler includes CKEditor only once.
+	 *
+	 * @error ckeditor-version-collision
+	 * @param {String} collidingVersion The version of the build which has already been (incorrectly) loaded.
+	 * @param {String} version The version of the build which is supposed to be loaded.
+	 */
+	log.error( 'ckeditor-version-collision: The global CKEDITOR_VERSION constant has already been set.', {
+		collidingVersion: windowOrGlobal.CKEDITOR_VERSION,
+		version
+	} );
+} else {
+	windowOrGlobal.CKEDITOR_VERSION = version;
+}

From bc3a340c44d5f6edd2d53c678dfa4f2f469f3615 Mon Sep 17 00:00:00 2001
From: Aleksander Nowodzinski <a.nowodzinski@cksource.com>
Date: Fri, 6 Jul 2018 17:32:31 +0200
Subject: [PATCH 2/3] Added root of the project to the dependencies in the
 package.json.

---
 package.json   | 3 +++
 src/version.js | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/package.json b/package.json
index 4b62899..4c1043c 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,9 @@
     "ckeditor 5",
     "ckeditor5-lib"
   ],
+  "dependencies": {
+	"ckeditor5": "^10.1.0"
+  },
   "devDependencies": {
     "@ckeditor/ckeditor5-core": "^10.1.0",
     "@ckeditor/ckeditor5-engine": "^10.1.0",
diff --git a/src/version.js b/src/version.js
index f3a09ea..86cf6f9 100644
--- a/src/version.js
+++ b/src/version.js
@@ -10,7 +10,7 @@
 /* global window, global */
 
 import log from './log';
-import { version } from '../package.json';
+import { version } from 'ckeditor5/package.json';
 
 const windowOrGlobal = typeof window === 'object' ? window : global;
 

From 6d62ae5961b2fc104a0165e040b8e3b86b84c2b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Piotrek=20Koszuli=C5=84ski?= <pkoszulinski@gmail.com>
Date: Tue, 10 Jul 2018 12:43:34 +0200
Subject: [PATCH 3/3] Docs and indentation.

---
 package.json   |  2 +-
 src/version.js | 38 ++++++++++++++++++++++++++++----------
 2 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/package.json b/package.json
index 103ae9b..92bf7eb 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,7 @@
     "ckeditor5-lib"
   ],
   "dependencies": {
-	"ckeditor5": "^10.1.0"
+    "ckeditor5": "^10.1.0"
   },
   "devDependencies": {
     "@ckeditor/ckeditor5-core": "^10.1.0",
diff --git a/src/version.js b/src/version.js
index 86cf6f9..a9a9b90 100644
--- a/src/version.js
+++ b/src/version.js
@@ -7,7 +7,7 @@
  * @module utils/version
  */
 
-/* global window, global */
+/* globals window, global */
 
 import log from './log';
 import { version } from 'ckeditor5/package.json';
@@ -16,15 +16,33 @@ const windowOrGlobal = typeof window === 'object' ? window : global;
 
 if ( windowOrGlobal.CKEDITOR_VERSION ) {
 	/**
-	 * This error is thrown when the base {@link module:core/editor/editor~Editor `Editor`}
-	 * class has been loaded twice (or more), a result of either:
-	 *
-	 * * the build containing two (or more) different versions of the {@link module:core/editor/editor~Editor `Editor`}
-	 * class – make sure **all** packages in your {@glink builds/index build} which have
-	 * `@ckeditor/ckeditor5-core` in their `package.json` [dependencies](https://docs.npmjs.com/files/package.json#dependencies)
-	 * use the same version of the package,
-	 * * two (or more) `ckeditor.js` builds loaded in the web page next to one another – check your web page for duplicated
-	 * `<script>` elements or make sure your page builder/bundler includes CKEditor only once.
+	 * This error is thrown when the `CKEDITOR_VERSION` global is being set more than once. This happens when in
+	 * two scenarios described above.
+	 *
+	 * # Some packages were duplicated
+	 *
+	 * CKEditor 5 was built from source packages which were duplicated during installation via npm.
+	 * Normally, npm deduplicates all packages so e.g. `@ckeditor/ckeditor5-core` is installed only once in `node_modules/`.
+	 * However, subsequent `npm install` calls or conflicting version dependencies may cause npm to install some packages
+	 * more than once. Furthermore, [npm in version 5+](https://github.com/npm/npm/issues/16991)
+	 * is also known for randomly failing to deduplicate packages.
+	 *
+	 * We recommend checking if any of the below steps helps:
+	 *
+	 * * `rm -rf node_modules && npm install` to make sure you have a clean `node_modules/` – this step
+	 * is known to help in majority of cases,
+	 * * check whether all CKEditor 5 packages are up to date and reinstall them
+	 * if you changed anything (`rm -rf node_modules && npm install`),
+	 * * downgrade npm to version 4 if you use a newer version.
+	 *
+	 * If all packages are correct and compatible with each other the above steps are known to help. If not, you may
+	 * try to check with `npm ls` how many times `@ckeditor/ckeditor5-core` is installed. If more than once, verify
+	 * which package causes that.
+	 *
+	 * # Two+ builds are loaded
+	 *
+	 * If you use CKEditor 5 builds, you might have loaded two (or more) `ckeditor.js` files in one web page
+	 * – check your web page for duplicated `<script>` elements or make sure your page builder/bundler includes CKEditor only once.
 	 *
 	 * @error ckeditor-version-collision
 	 * @param {String} collidingVersion The version of the build which has already been (incorrectly) loaded.