stack_trace_fixer.ts

// Node used to lose track of stack frames across async gaps.  But due to improvements
// in V8, Node 14.x will now preserve stack frames for `async` functions.
//
// Unfortunately, this doesn't work for raw promises and most libraries on NPM either
// use raw promises or are transpiled down to raw promises.
//
// To counter this, you can use this wrapper whenever you're calling into a library
// that returns a raw promise:
// - OLD: const result = await someLibrary.query(...);
// - NEW: const result = await stackTraceFixer.wrap(someLibrary.query(...));

export async function wrap<T>(promise: Promise<T>): Promise<T> {
    try {
        return await promise;
    } catch (err) {
        graft(1, err);
        throw err;
    }
}

// Append the current stack trace to the end of `err.stack`.
// - skipStackFrames: The number of top-most frames of the current stack trace to skip.
export function graft(skipStackFrames: number, err: Error): void {
    const stack = new Error().stack;
    if (stack === undefined) {
        console.log('Warning: Stack trace is undefined.');
        return;
    }

    // The first line is the exception message.  The second is our stack frame.  Remove both.
    const skipLines = skipStackFrames + 2;
    let pos = 0;
    for (let i = 0; i < skipLines; i++) {
        pos = stack.indexOf('\n', pos + 1);
        if (pos < 0) {
            console.log(`Warning: Tried to trim ${skipLines} lines; only found ${i}.`);
            return;
        }
    }

    err.stack = err.stack + stack.substring(pos + 1);
}