Don't request the deprecated navigation areas endpoint outside of the…

… Gutenberg plugin (#37187)

* Only call useEntityProp when process.env.GUTENBERG_PHASE === 2 )

* Give setAreaMenu a default value so that it can be safely called

packages/block-library/src/navigation/edit/index.js

@@ -2,6 +2,7 @@
  * External dependencies
  */
 import classnames from 'classnames';
+import noop from 'lodash';
 
 /**
  * WordPress dependencies
@@ -109,12 +110,19 @@ function Navigation( {
 		layout: { justifyContent, orientation = 'horizontal' } = {},
 	} = attributes;
 
-	const [ areaMenu, setAreaMenu ] = useEntityProp(
-		'root',
-		'navigationArea',
-		'navigation',
-		navigationArea
-	);
+	let areaMenu,
+		setAreaMenu = noop;
+	// Navigation areas are deprecated and on their way out. Let's not perform
+	// the request unless we're in an environment where the endpoint exists.
+	if ( process.env.GUTENBERG_PHASE === 2 ) {
+		// eslint-disable-next-line react-hooks/rules-of-hooks
+		[ areaMenu, setAreaMenu ] = useEntityProp(
+			'root',
+			'navigationArea',
+			'navigation',
+			navigationArea
+		);
+	}
 
 	const navigationAreaMenu = areaMenu === 0 ? undefined : areaMenu;