"ble_uart" : Unhandled promise rejection

[espruino-discuss]

Posted at 2021-09-07 by @MaBecker

used code:

bleSendJS = function(_id, _cmd) {
    console.log('s');
    NRF.requestDevice({timeout: 5E3, filters: [{ id: _id }] }).then(function(device) {
        console.log('f');
        console.log(device);
        return require("ble_uart").connect(device);
    }).then(function(uart) {
        console.log('c');
        var data;
        uart.on('data', function(d) {
            data += d;
        });
        uart.write(`\x03\x10(${_cmd})\n`).then(function() {
            setTimeout(function() {
                uart.disconnect();
                console.log('output:',data);
                console.log("Disconnected");
            }, 2000);
        });
    }).catch(function(e) {
        console.log("ERROR:", e);
    });
};

output

>bleSendJS(id, nl1);
=undefined
BluetoothDevice: {
  "id": "d5:c7:e2:67:ac:f0 random",
  "rssi": -81,
  "data": new Uint8Array([2, 1, 6, 12, 9, 73, 79, 50, 52, 52, 55, 32, 97, 99, 102, 48]).buffer
 }
ERROR: Disconnected
Uncaught Error: Unhandled promise rejection: Error: Unhandled promise rejection: InternalError: BLE task completed that wasn't scheduled (4/0)
>

Is there a way to avoid that?

[espruino-discuss]

Posted at 2021-09-08 by Robin

Tue 2021.09.07

It appears that the error may be caused and thrown from within the disconnect() function at L15

http://www.espruino.com/Reference#t_l_BluetoothRemoteGATTServer_disconnect

function BluetoothRemoteGATTServer.disconnect()
Returns: A Promise that is resolved (or rejected) when the disconnection is complete (non-standard)

See Note: 'In Espruino we return a Promise to make it easier to detect when Espruino is free to connect to something else.'

That said, I thought it would be a breeze to add detection code, but code location and the syntax is a bit different with nested functions.
Maybe this might provide some clues:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch

[gfwilliams]

Posted at 2021-09-14 by @gfwilliams

uart.write( returns a promise, and you're not handling the rejection of that - so that might be the Unhandled promise rejection you're not managing to handle?

[espruino-discuss]

Posted at 2021-09-14 by @MaBecker

Ok, so like this?

        uart.write(`\x03\x10(${_cmd})\n`).then(function() {
            setTimeout(function() {
                uart.disconnect();
                console.log('output:',data);
                console.log("Disconnected");
            }, 2000);
        }).catch(function () {
            console.log("Promise Rejected - disconnect");
            uart.diconnect();
        });

[gfwilliams]

Posted at 2021-09-15 by @gfwilliams

Yes, that should help

[espruino-discuss]

Posted at 2021-09-22 by @MaBecker

There is the need for a additional try catch to handle Uncaught Error: BLE task DISCONNECT is already in progress

bleSendJS = function(_id, _cmd) {
    console.log('s');
    try {
        NRF.requestDevice({ timeout: 5E3, filters: [{ id: _id }] }).then(function(device) {
            console.log('f');
            console.log(device);
            return require("ble_uart").connect(device);
        }).then(function(uart) {
            console.log('c');
            var data;
            uart.on('data', function(d) {
                data += d;
            });
            uart.write(`\x03\x10(${_cmd})\n`).then(function() {
                setTimeout(function() {
                    uart.disconnect();
                    console.log('output:', data);
                    console.log("Disconnected");
                }, 2000);
            }).catch(function() {
                console.log("Promise Rejected - disconnect");
                uart.diconnect();
            });
        }).catch(function(e) {
            console.log("ERROR:", e);
        });
    } catch (e) {
        console.log("ERROR:", e);
    }
};

[espruino-discuss]

Posted at 2021-09-25 by Robin

Sat 2021.09.25

Without writing any code or testing on my part;

I originally thought the try/catch would have to wrap/start at L14 as the user forced disconnect is within the setInterval(). So is that the promise reponse isn't really attached to any code as it responds, that the catch wrapper had to be around the entire code block as you have shown perhaps?

In any event, thank you for the snippet @MaBecker as this will come in handy down the road. . . .