Fix isGalleryV2Enabled calculation for the native version

packages/block-library/src/gallery/shared.js

@@ -3,6 +3,11 @@
  */
 import { get, pick } from 'lodash';
 
+/**
+ * WordPress dependencies
+ */
+import { Platform } from '@wordpress/element';
+
 export function defaultColumnsNumber( imageCount ) {
 	return imageCount ? Math.min( 3, imageCount ) : 3;
 }
@@ -23,25 +28,33 @@ export const pickRelevantMediaFiles = ( image, sizeSlug = 'large' ) => {
 	return imageProps;
 };
 
+function getGalleryBlockV2Enabled() {
+	// We want to fail early here, at least during beta testing phase, to ensure
+	// there aren't instances where undefined values cause false negatives.
+	if ( ! window.wp || typeof window.wp.galleryBlockV2Enabled !== 'boolean' ) {
+		throw 'window.wp.galleryBlockV2Enabled is not defined';
+	}
+	return window.wp.galleryBlockV2Enabled;
+}
+
 /**
  * The new gallery block format is not compatible with the use_BalanceTags option
  * in WP versions <= 5.8 https://core.trac.wordpress.org/ticket/54130. The
  * window.wp.galleryBlockV2Enabled flag is set in lib/compat.php. This method
  * can be removed when minimum supported WP version >=5.9.
  */
 export function isGalleryV2Enabled() {
+	// The logic for the native version is located in a different if statement
+	// due to the fact that the `process.env.IS_GUTENBERG_PLUGIN` constant
+	// should only be used as the condition in an if statement.
+	if ( Platform.isNative ) {
+		return getGalleryBlockV2Enabled();
+	}
+
 	// Only run the Gallery version compat check if the plugin is running, otherwise
 	// assume we are in 5.9 core and enable by default.
 	if ( process.env.IS_GUTENBERG_PLUGIN ) {
-		// We want to fail early here, at least during beta testing phase, to ensure
-		// there aren't instances where undefined values cause false negatives.
-		if (
-			! window.wp ||
-			typeof window.wp.galleryBlockV2Enabled !== 'boolean'
-		) {
-			throw 'window.wp.galleryBlockV2Enabled is not defined';
-		}
-		return window.wp.galleryBlockV2Enabled;
+		return getGalleryBlockV2Enabled();
 	}
 
 	return true;