[jupyter-kernel] stack trace line numbers are wrong

[skybrian]

To reproduce:

• Create a new Jupyter Notebook in VS Code.
• Set the kernel to Deno. (Seems to be ~/.deno/bin/deno.)
• Enter the following code:

console.log("1");
console.log("2");
console.log("3");
throw new Error("fail");

The output is a stack trace:

Stack trace:
Error: fail
    at <anonymous>:5:7

So this is off by 1.

But this gets worse for classes:

class Camera {
    constructor(public x: number, public y: number, public dir: number) {}

    get pos(): [number, number] {
        return [this.x, this.y];
    }

    get dirVector(): [number, number] {
        return [Math.cos(this.dir * Math.PI / 180), Math.sin(this.dir * Math.PI / 180)];
    }

    get left(): [number, number] {
        const half_width = params.camera_width / 2;
        const dir = (this.dir - half_width) * Math.PI / 180;
        return [Math.cos(dir), Math.sin(dir)];
    }

    get right(): [number, number] {
        const half_width = params.camera_width / 2;
        const dir = (this.dir + half_width) * Math.PI / 180;
        return [Math.cos(dir), Math.sin(dir)];
    }
}

throw new Error("fail");

The stack trace I get is:

Stack trace:
Error: fail
    at <anonymous>:40:7

The actual line number is 25. I suspect the JavaScript line number isn't getting run through a sourcemap to get the TypeScript line number?

(Also, this is more of a feature request, but it would be friendlier to reproduce the source code in the error message like Python does, since cells don't have line numbers turned on by default.)

[nayeemrmn]

This is also a problem with deno repl which the jupyter kernel uses. I don't think think there's a pre-existing tracking issue

[bartlomieju]

@nayeemrmn could you handle source mapping in REPL?