add @codemirror/merge

packages/editor/package.json

@@ -28,6 +28,7 @@
     "@codemirror/lang-markdown": "^6.2.0",
     "@codemirror/language": "^6.8.0",
     "@codemirror/language-data": "^6.3.1",
+    "@codemirror/merge": "6.0.0",
     "@codemirror/state": "^6.2.1",
     "@codemirror/view": "^6.15.3",
     "@popperjs/core": "^2.11.8",

yarn.lock

@@ -1506,6 +1506,14 @@
     "@codemirror/view" "^6.0.0"
     crelt "^1.0.5"
 
+"@codemirror/merge@6.0.0":
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/@codemirror/merge/-/merge-6.0.0.tgz#69c4877437bc0a75ff9984da1f5dabb5d88301a6"
+  integrity sha512-dxdUIQRxgC+xqzBtfY5zjgDIR38Xp6iycb8Lp1Q2gzEkX9y/UrqOAOlpqU3kfDBa0wGHrjlSYzpcQ/lXWG/59w==
+  dependencies:
+    "@codemirror/state" "^6.0.0"
+    "@codemirror/view" "^6.0.0"
+
 "@codemirror/search@^6.0.0":
   version "6.5.0"
   resolved "https://registry.yarnpkg.com/@codemirror/search/-/search-6.5.0.tgz#308f9968434e0e6ed59c9ec36a0239eb1dfc5d92"