Panic error when i used 5 vus

Grafana
1

Hello,

I have an issue with a script I am working on. The beginning of the script is an API request, then I switch to using the browser. When I run the script unit-wise, I never encounter the error. However, when I run 25 iterations on 5 virtual users, I often get errors like this:

panic: runtime error: index out of range [5] with length 0 [recovered]
running panic: runtime error: index out of range [5] with length 0
ui     [==============>-----------------------] 5 VUs  00m44.9s/10m0s  10/25 shared iters
goroutine 27702 [running]:
github.com/dop251/goja.(*vm).handleThrow(0xc00055e000, {0x1a07c60, 0xc0096e6870})
        github.com/dop251/goja@v0.0.0-20240610225006-393f6d42497b/vm.go:788 +0x405
github.com/dop251/goja.(*vm).runTryInner.func1()
        github.com/dop251/goja@v0.0.0-20240610225006-393f6d42497b/vm.go:830 +0x3f
panic({0x1a07c60?, 0xc0096e6870?})
        runtime/panic.go:770 +0x132

Do you have any ideas? I’ve tried a lot of things today. Here’s my script:

import http from 'k6/http';
import { browser } from 'k6/browser';
import { check, sleep } from 'k6';
import { Trend } from 'k6/metrics';
import { Counter } from 'k6/metrics';
import { Rate } from "k6/metrics";
import { URL } from 'https://jslib.k6.io/url/1.0.0/index.js';

// Configuration of execution mode
function getOptions(mode) {
    switch (mode) {
        case 'shared-iterations':
            return {
                scenarios: {
                    ui: {
                        executor: 'shared-iterations',
                        exec: 'callEasySignO2S',
                        vus: 5,
                        iterations: 25,
                        options: {
                            browser: {
                                type: 'chromium',
                                headless: "new"
                            }
                        }
                    }
                }
            };
        case 'dev':
            return {
                scenarios: {
                    browser: {
                        executor: 'shared-iterations',
                        exec: 'callEasySignO2S',
                        vus: 1,
                        iterations: 1,
                        options: {
                            browser: {
                                type: 'chromium',
                                headless: false
                            }
                        }
                    }
                }
            };
        default:
            throw new Error("Invalid mode. Please pass the EXECUTOR_MODE option: <name>");
    }
}
const mode = __ENV.EXECUTOR_MODE || 'shared-iterations';
export const options = getOptions(mode);

export async function script() {
    const page = await browser.newPage();

    try {
        await page.goto(signatureURL, { waitUntil: 'load' });
        await page.setViewportSize({ width: 1920, height: 1080 });
        await page.waitForLoadState('load');
        await page.waitForLoadState('domcontentloaded');
        await page.click('button#js--zoom-out-btn');
        await page.evaluate(() => window.performance.mark('debut'));
        await page.click('button#js--zoom-out-btn');
        await page.click('button#js--zoom-out-btn');
        await page.click('button#js--zoom-out-btn');
        await page.click('button#js--zoom-out-btn');
        await page.click('button#js--zoom-in-btn');
        await page.click('button#js--zoom-in-btn');
        await page.click('button#js--zoom-in-btn');
        await page.waitForFunction(() => {
            const button = document.querySelector('button.js-btn-sign');
            return button && !button.hasAttribute('disabled');
        }, { timeout: 30000 });
        await page.click('.btn.btn-primary.js-btn-sign.mx-auto.btn-large.js-btn');
        await page.waitForLoadState('load');
        await page.waitForLoadState('domcontentloaded');
        await page.click('input#agreementCheckbox-contraliaCGU');
        await page.click('input#agreementCheckbox-certinomisCGU');
        await page.click('input#agreementCheckbox-checkbox1');
        await page.click('input#agreementCheckbox-checkbox2');
        await page.click('button#js-summaryNextBtn-1');
        await page.waitForSelector('#js-summaryNextBtn-1');
        await page.waitForLoadState('load');
        await page.waitForLoadState('domcontentloaded');

        const maxAttempts = 3;

        for (let attemptIndex = 0; attemptIndex < maxAttempts; attemptIndex++) {
            const buttonEnabled = await page.evaluate(() => {
                const button = document.querySelector('button.js-otp-sign-button');
                return button && button.getAttribute('aria-disabled') === 'false';
            });

            if (buttonEnabled) {
                console.log("The button is enabled, you can continue.");
                break;
            } else {
                console.log(`The button is disabled, attempt ${attemptIndex + 1}...`);
                await page.fill('input#js-otp-input-1', '000000');
            }
        }

        await page.click('.js-otp-sign-button');
        await page.evaluate(() => window.performance.mark('fin'));
        await page.evaluate(() => window.performance.measure('tempsSignature', 'debut', 'fin'));
        const signature = await page.evaluate(() =>
            JSON.parse(
                JSON.stringify(
                    window.performance.getEntriesByName("tempsSignature")
                )
            )[0].duration
        );
        signatureFront.add(signature);
        await page.waitForLoadState();
    } catch (error) {
        errorSignature.add(1);
        console.error('Error: An exception has occurred');
        console.error('Error:', error.message);
        console.error('Stack Trace:', error.stack);
    } finally {
        console.log('PAGE CLOSED');
        await page.close();
    }
}

Thank you in advance for your help.