Bugs with new n8n Form nodes

[barn4k]

Bug Description

I have two similar issues with the new Form nodes.
The first one is that it return the Error 500 if there is only the trigger node and Form ending node (no Next Page nodes in-between)
The second issue is with the Form ending node, which becomes broken if I sent an expression to it

Both issues will result in Error 500, but with different error text.
For the first one:

For the second one:

To Reproduce

First issue:

{
  "meta": {
    "instanceId": "ea8ccd7cb9d9fc233a4683c7569b952c9669ba9d3ba1459d89a9944d357fa5b3"
  },
  "nodes": [
    {
      "parameters": {
        "formTitle": "Lambda payload generator",
        "formDescription": "descr",
        "formFields": {
          "values": [
            {
              "fieldLabel": "Press the Next button"
            }
          ]
        },
        "options": {
          "buttonLabel": "Next"
        }
      },
      "id": "5deca3ea-0469-4ed0-80ac-a255ecb5fd04",
      "name": "On form submission",
      "type": "n8n-nodes-base.formTrigger",
      "typeVersion": 2.2,
      "position": [
        960,
        680
      ],
      "webhookId": "411cbebe-fa97-434b-a096-894992c9974d"
    },
    {
      "parameters": {
        "operation": "completion",
        "completionTitle": "title",
        "completionMessage": "=message:\n{{ $json }}",
        "options": {}
      },
      "id": "4a787dc6-27ad-400f-aefc-96be5c5daf33",
      "name": "Form2",
      "type": "n8n-nodes-base.form",
      "typeVersion": 1,
      "position": [
        1200,
        680
      ],
      "webhookId": "31884a7b-0b43-45e0-bf4c-43fb2e20ab60"
    }
  ],
  "connections": {
    "On form submission": {
      "main": [
        [
          {
            "node": "Form2",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {}
}

Second issue

{
  "meta": {
    "instanceId": "ea8ccd7cb9d9fc233a4683c7569b952c9669ba9d3ba1459d89a9944d357fa5b3"
  },
  "nodes": [
    {
      "parameters": {
        "formTitle": "Lambda payload generator",
        "formDescription": "descr",
        "formFields": {
          "values": [
            {
              "fieldLabel": "Press the Next button"
            }
          ]
        },
        "options": {
          "buttonLabel": "Next"
        }
      },
      "id": "5deca3ea-0469-4ed0-80ac-a255ecb5fd04",
      "name": "On form submission",
      "type": "n8n-nodes-base.formTrigger",
      "typeVersion": 2.2,
      "position": [
        1000,
        480
      ],
      "webhookId": "411cbebe-fa97-434b-a096-894992c9974d"
    },
    {
      "parameters": {
        "operation": "completion",
        "completionTitle": "title",
        "completionMessage": "=message: {{ JSON.stringify($json.action) }}",
        "options": {}
      },
      "id": "0a429fa0-6da0-4a03-8d2b-8df50e896e9c",
      "name": "Form",
      "type": "n8n-nodes-base.form",
      "typeVersion": 1,
      "position": [
        1620,
        480
      ],
      "webhookId": "31884a7b-0b43-45e0-bf4c-43fb2e20ab60"
    },
    {
      "parameters": {
        "jsCode": "return [\n  {\n    \"action\": \"some action\",\n    \"params\": {\n      \"upn\": \"[email protected]\",\n      \"query\": \"\",\n      \"max_req\": \"\"\n    },\n    \"settings\": {\n      \"show_input\": false\n    }\n  }\n]"
      },
      "id": "0949d804-d638-44d0-904a-2f370c7fc94b",
      "name": "Code",
      "type": "n8n-nodes-base.code",
      "typeVersion": 2,
      "position": [
        1420,
        480
      ]
    },
    {
      "parameters": {
        "formFields": {
          "values": [
            {
              "fieldLabel": "Press the end button"
            }
          ]
        },
        "options": {
          "buttonLabel": "End"
        }
      },
      "id": "74b3082c-608d-42d6-9d8f-cef00bc38dc6",
      "name": "Form1",
      "type": "n8n-nodes-base.form",
      "typeVersion": 1,
      "position": [
        1200,
        480
      ],
      "webhookId": "c077fa53-1bc0-4c89-9233-d597b0b56e71"
    }
  ],
  "connections": {
    "On form submission": {
      "main": [
        [
          {
            "node": "Form1",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Code": {
      "main": [
        [
          {
            "node": "Form",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Form1": {
      "main": [
        [
          {
            "node": "Code",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "pinData": {}
}

Expected behavior

The Ending node will proper return the output

Operating System

cloud

n8n Version

1.68.0

Node.js Version

cloud

Database

SQLite (default)

Execution mode

main (default)

[Joffcom]

Hey @barn4k,

We have created an internal ticket to look into this which we will be tracking as "GHC-470"

[Joffcom]

Hey @barn4k,

Issue 2 was fixed in yesterdays release with this PR: #11781

Issue 1 looks to be broken still.