Exception: LinkOutNode.prototype.onMessage: cannot coerce undefined to object!

[ralphwetzel]

The design of the (standard) LinkNodes looks a bit strange to me: Although the LinkOutNode shown in the picture definitely has no link to another (LinkIn) node, it's links property is populated. The id shown does not exist (anymore?) in any of my flows.

In nodered.js the call @ line 849 to RED.nodes.getNode(link) w/ this non-existing id returns undefined: https://github.com/phoddie/node-red-mcu/blob/7d9f7630e0bb17d00edd00ab56f32758acc66789/nodered.js#L842-L850

Later, when a msg arrives, links[i] @ links[i].send(msg) (line 855) will be that returned undefined. Consequentially, an exception is thrown: LinkOutNode.prototype.onMessage: cannot coerce undefined to object! https://github.com/phoddie/node-red-mcu/blob/7d9f7630e0bb17d00edd00ab56f32758acc66789/nodered.js#L851-L861

I propose to replace line 849 by a classical loop checking if the (link) id references an existing node:

            this.#links = [];
            for (let i=0, l=config.links.length; i<l; i++) {
                let n = RED.nodes.getNode(config.links[i]);
                if (n) this.#links.push(n);
            }

[phoddie]

If I understand the report correctly, the problem is that the link is broken -- that one or more of the node ID values in the links array references a node that no longer exists? I had expected Node-RED would clean that up. If that is really happening, then that's something that nodered2mcu should clean-up so the runtime doesn't have to be account for it. Would you mind posting an example flows.json that shows the problem so I can investigate? Thank you!

[ralphwetzel]

Here's a flow showing the same issue.

It even references two non existing nodes in its links property:

[
    {
        "id": "f36e3774a30673e3",
        "type": "tab",
        "label": "Flow 6",
        "disabled": false,
        "info": "",
        "env": [],
        "_mcu": {
            "mcu": false
        }
    },
    {
        "id": "b1ee8cbb775e3213",
        "type": "link in",
        "z": "f36e3774a30673e3",
        "name": "link in 36",
        "links": [
            "7ecd205bebc32369"
        ],
        "_mcu": {
            "mcu": false
        },
        "x": 555,
        "y": 540,
        "wires": [
            [
                "1ecc56b11d08ed72"
            ]
        ]
    },
    {
        "id": "7ecd205bebc32369",
        "type": "link out",
        "z": "f36e3774a30673e3",
        "name": "link out 46",
        "mode": "link",
        "links": [
            "316aa1d3398a969d",
            "b2d692753dcb51e4",
            "b1ee8cbb775e3213"
        ],
        "_mcu": {
            "mcu": false
        },
        "x": 485,
        "y": 540,
        "wires": []
    },
    {
        "id": "1ecc56b11d08ed72",
        "type": "debug",
        "z": "f36e3774a30673e3",
        "name": "debug 32",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "_mcu": {
            "mcu": false
        },
        "x": 660,
        "y": 540,
        "wires": []
    },
    {
        "id": "cf0c5a63e767b787",
        "type": "inject",
        "z": "f36e3774a30673e3",
        "name": "",
        "props": [
            {
                "p": "payload"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "",
        "payload": "",
        "payloadType": "date",
        "_mcu": {
            "mcu": false
        },
        "x": 380,
        "y": 540,
        "wires": [
            [
                "7ecd205bebc32369"
            ]
        ]
    }
]

[phoddie]

Thank you for the flow. I have an update to nodered2mcu that removes broken references in the links array. That avoids the runtime error later. That'll be included in a Moddable SDK update in a day or so.

I also fixed some bit-rot that caused the link call nodes to fail. The problem was introduced when the switch was made to use structuredClone to duplicate messages. That's committed to the Node-RED MCU repository.

[phoddie]

I think this is now fixed. Would you please confirm?

[ralphwetzel]

It is! Thank you! 👍