fix(editor): Fix issue that frontend breaks with unkown nodes (#7596)

Because of recent changes does the frontend break when a node is not
known.

![Screenshot from 2023-11-03
08-27-43](https://github.com/n8n-io/n8n/assets/6249596/ab340c3c-9b72-4220-b1f8-70d80f7a5522)



Github issue / Community forum post (link here to close automatically):

---------

Signed-off-by: Oleg Ivaniv <me@olegivaniv.com>
Co-authored-by: Oleg Ivaniv <me@olegivaniv.com>

cypress/fixtures/workflow-with-unknown-nodes.json

@@ -0,0 +1,90 @@
+{
+  "meta": {
+    "instanceId": "15bbf37b6a515ccc2f534cabcd8bd171ca33583ff7744b1e9420e5ce68e615bb"
+  },
+  "nodes": [
+    {
+      "parameters": {},
+      "id": "40720511-19b6-4421-bdb0-3fb6efef4bc5",
+      "name": "When clicking \"Execute Workflow\"",
+      "type": "n8n-nodes-base.manualTrigger",
+      "typeVersion": 1,
+      "position": [
+        280,
+        320
+      ]
+    },
+    {
+      "parameters": {},
+      "id": "acdd1bdc-c642-4ea6-ad67-f4201b640cfa",
+      "name": "Unknown node 1",
+      "type": "n8n-nodes-base.thisNodeDoesntExist",
+      "typeVersion": 1,
+      "position": [
+        400,
+        500
+      ]
+    },
+		{
+      "parameters": {},
+      "id": "acdd1bdc-c642-4ea6-ad67-f4201b640ffa",
+      "name": "Unknown node 2",
+      "type": "n8n-nodes-base.thisNodeDoesntExistEither",
+      "typeVersion": 1,
+      "position": [
+        600,
+        500
+      ]
+    },
+    {
+      "parameters": {
+        "options": {}
+      },
+      "id": "fbe5163b-7474-4741-980a-e4956789be0a",
+      "name": "Edit Fields",
+      "type": "n8n-nodes-base.set",
+      "typeVersion": 3.2,
+      "position": [
+        500,
+        320
+      ]
+    },
+    {
+      "parameters": {
+        "options": {}
+      },
+      "id": "163313b9-64ff-4ffc-b00f-09b267d8132c",
+      "name": "Edit Fields1",
+      "type": "n8n-nodes-base.set",
+      "typeVersion": 3.2,
+      "position": [
+        720,
+        320
+      ]
+    }
+  ],
+  "connections": {
+    "When clicking \"Execute Workflow\"": {
+      "main": [
+        [
+          {
+            "node": "Edit Fields",
+            "type": "main",
+            "index": 0
+          }
+        ]
+      ]
+    },
+    "Edit Fields": {
+      "main": [
+        [
+          {
+            "node": "Edit Fields1",
+            "type": "main",
+            "index": 0
+          }
+        ]
+      ]
+    }
+  }
+}