Issue #3607961: Fatal error - $methods must be of type array, string given

StaticRouteDiscoveryBase::createRoute() requires the $methods argument to be
an array as of Drupal 11.4. gutenberg.routing.yml declares HTTP methods as
plain strings (methods: 'GET'), which triggers:

  TypeError: Drupal\Core\Routing\StaticRouteDiscoveryBase::createRoute():
  Argument #7 ($methods) must be of type array, string given

Wrap every method declaration in an array (methods: ['GET']).

Reproduced on: Gutenberg 3.0.6, Drupal core 11.4.

diff --git a/gutenberg.routing.yml b/gutenberg.routing.yml
--- a/gutenberg.routing.yml
+++ b/gutenberg.routing.yml
@@ -18,7 +18,7 @@
   path: '/editor/media/upload/{editor}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\MediaController::upload'
-  methods: 'POST'
+  methods: ['POST']
   requirements:
     _entity_access: 'editor.use'
     _permission: 'use gutenberg'
@@ -31,7 +31,7 @@
     parameters:
       file:
         type: entity:file
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -42,7 +42,7 @@
     parameters:
       file:
         type: entity:file
-  methods: 'POST'
+  methods: ['POST']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -51,7 +51,7 @@
   path: '/editor/media/load-media/{media}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\MediaController::loadMedia'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -64,7 +64,7 @@
     # administration theme when editing or creating content' setting enabled.
     # @see \Drupal\node\EventSubscriber\NodeAdminRouteSubscriber::alterRoutes()
     _node_operation_route: TRUE
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -72,7 +72,7 @@
   path: '/editor/media/render/{media}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\MediaController::render'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -80,7 +80,7 @@
   path: '/editor/entity/render/{entity_type}/{entity_id}/{view_mode}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\EntityController::renderEntity'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -88,7 +88,7 @@
   path: '/editor/entity/view_modes/{entity_type}/{bundle}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\EntityController::viewModes'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -97,7 +97,7 @@
   defaults:
     _controller: '\Drupal\gutenberg\Controller\BlocksController::loadByType'
     content_type: 'none'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -108,7 +108,7 @@
     # parameters:
     #   block:
     #     type: entity:block
-  methods: 'POST'
+  methods: ['POST']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -117,7 +117,7 @@
   defaults:
     _controller: '\Drupal\gutenberg\Controller\BlocksController::loadContentBlockTypes'
     content_type: 'none'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -132,7 +132,7 @@
   path: '/editor/content_block/clone_if_used'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\BlocksController::cloneIfUsed'
-  methods: 'POST'
+  methods: ['POST']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -169,7 +169,7 @@
   path: '/editor/reusable-blocks'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\ReusableBlocksController::save'
-  methods: 'POST'
+  methods: ['POST']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -178,7 +178,7 @@
   path: '/editor/reusable-blocks/{block_id}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\ReusableBlocksController::save'
-  methods: 'PUT'
+  methods: ['PUT']
   requirements:
     _custom_access: '\Drupal\gutenberg\Controller\ReusableBlocksController::access'
     _format: json
@@ -187,7 +187,7 @@
   path: '/editor/reusable-blocks/{block_id}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\ReusableBlocksController::delete'
-  methods: 'DELETE'
+  methods: ['DELETE']
   requirements:
     _custom_access: '\Drupal\gutenberg\Controller\ReusableBlocksController::access'
     _format: json
@@ -196,7 +196,7 @@
   path: '/editor/reusable-blocks'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\ReusableBlocksController::load'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -204,7 +204,7 @@
   path: '/editor/reusable-blocks/{block_id}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\ReusableBlocksController::load'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _custom_access: '\Drupal\gutenberg\Controller\ReusableBlocksController::access'
     _format: json
@@ -212,7 +212,7 @@
   path: '/editor/patterns/categories'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\ReusableBlocksController::categoryLoad'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -223,7 +223,7 @@
     parameters:
       category:
         type: entity:taxonomy_term
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _custom_access: '\Drupal\gutenberg\Controller\ReusableBlocksController::access'
     _format: json
@@ -231,7 +231,7 @@
   path: '/editor/patterns/categories'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\ReusableBlocksController::categoryCreate'
-  methods: 'POST'
+  methods: ['POST']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -241,7 +241,7 @@
   defaults:
     _controller: '\Drupal\gutenberg\Controller\OEmbedProxyUrlController::request'
     _disable_route_normalizer: 'TRUE'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -249,7 +249,7 @@
   path: '/editor/search'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\SearchController::search'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -257,7 +257,7 @@
   path: '/editor/media/search/{type}/{search}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\MediaController::search'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -265,7 +265,7 @@
   path: '/editor/media/update_data/{fid}'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\MediaController::updateData'
-  methods: 'POST'
+  methods: ['POST']
   requirements:
     _permission: 'use gutenberg'
     _format: json
@@ -274,7 +274,7 @@
   path: '/editor/media/autocomplete'
   defaults:
     _controller: '\Drupal\gutenberg\Controller\MediaController::autocomplete'
-  methods: 'GET'
+  methods: ['GET']
   requirements:
     _permission: 'use gutenberg'
     _format: json