Allow passing of title to default error page (#7381)

* Allow passing of title to default error page

* Update README to include Error#title information

* Change title init location

* Update _error.js

packages/next/README.md

@@ -1398,7 +1398,9 @@ class Page extends React.Component {
 export default Page
 ```
 
-> If you have created a custom error page you have to import your own `_error` component from `./_error` instead of `next/error`
+> If you have created a custom error page you have to import your own `_error` component from `./_error` instead of `next/error`.
+
+The Error module also takes `title` as a property if you want to pass in message text along with a `statusCode`.
 
 ### Custom configuration
 

packages/next/pages/_error.tsx

@@ -27,7 +27,7 @@ export default class Error<P = {}> extends React.Component<P & ErrorProps> {
 
   render() {
     const { statusCode } = this.props
-    const title = statusCodes[statusCode] || 'An unexpected error has occurred'
+    const title = this.props.title || statusCodes[statusCode] || 'An unexpected error has occurred'
 
     return (
       <div style={styles.error}>