Merge pull request #6116 from electron/extensions-app-ready

Mark which APIs are unavailable before app ready

docs/api/browser-window.md

@@ -438,12 +438,18 @@ console.
 
 Method will also not return if the extension's manifest is missing or incomplete.
 
+**Note:** This API cannot be called before the `ready` event of the `app` module
+is emitted.
+
 ### `BrowserWindow.removeDevToolsExtension(name)`
 
 * `name` String
 
 Remove the DevTools extension whose name is `name`.
 
+**Note:** This API cannot be called before the `ready` event of the `app` module
+is emitted.
+
 ### `BrowserWindow.getDevToolsExtensions()`
 
 Returns an Object where the keys are the extension names and each value is
@@ -455,6 +461,9 @@ To check if a DevTools extension is installed you can run the following:
 let installed = BrowserWindow.getDevToolsExtensions().hasOwnProperty('devtron')
 ```
 
+**Note:** This API cannot be called before the `ready` event of the `app` module
+is emitted.
+
 ## Instance Properties
 
 Objects created with `new BrowserWindow` have the following properties: