Google Cloud Function returns vague 'Connection error' when trying to connect to Google CloudSQL (mysql) instance

I was trying out this codelab code snippet by Google. I wanted to alter it in a way so that the Vision API metadata would be stored in a relational MySQL using the CloudSQL service - following their examples on how to connect Cloud Functions with CloudSQL.

The code I ended up deploys but upon triggering the function (by uploading a new image) I get a vague 'connection error' in the logs with no more information. This is my code at this moment:

const vision = require('@google-cloud/vision');
const Storage = require('@google-cloud/storage');
 
const client = new vision.ImageAnnotatorClient();

const winston = require('winston');
const {LoggingWinston} = require('@google-cloud/logging-winston');
const loggingWinston = new LoggingWinston();
const logger = winston.createLogger({
  level: 'info',
  transports: [new winston.transports.Console(), loggingWinston],
});

const createUnixSocketPool = async (config) => {
  const dbSocketPath = "/cloudsql"
  return await mysql.createPool({
    user: 'root',
    password: 'mypassword',
    database: 'mydatabase',
    socketPath: `${dbSocketPath}/cs-03-282615:europe-west1:mydatabase`,
    ...config
  });
}
 
const createPool = async () => {
  const config = {

    connectionLimit: 5,
    connectTimeout: 10000,
    acquireTimeout: 10000,
    waitForConnections: true,
    queueLimit: 0,
  }
    return await createUnixSocketPool(config); 
};

let pool;
const poolPromise = createPool()
  .then(async (pool) => {
    return pool;
  })
  .catch((err) => {
    logger.error(err);
    process.exit(1)
  });
 
exports.vision_analysis = async (event, context, pool) => {
    console.log(`Event: ${JSON.stringify(event)}`);
 
    const filename = event.name;
    const filebucket = event.bucket;
 
    console.log(`New picture uploaded ${filename} in ${filebucket}`);
 
    const request = {
        image: { source: { imageUri: `gs://${filebucket}/${filename}` } },
        features: [
            { type: 'LABEL_DETECTION' },
            { type: 'IMAGE_PROPERTIES' },
            { type: 'SAFE_SEARCH_DETECTION' }
        ]
    };
 
    // invoking the Vision API
    const [response] = await client.annotateImage(request);
    console.log(`Raw vision output for: ${filename}: ${JSON.stringify(response)}`);
 
    if (response.error === null) {
        // listing the labels found in the picture
        const labels = response.labelAnnotations
            .sort((ann1, ann2) => ann2.score - ann1.score)
            .map(ann => ann.description)
        console.log(`Labels: ${labels.join(', ')}`);
 
        // retrieving the dominant color of the picture
        const color = response.imagePropertiesAnnotation.dominantColors.colors
            .sort((c1, c2) => c2.score - c1.score)[0].color;
        const colorHex = decColorToHex(color.red, color.green, color.blue);
        console.log(`Colors: ${colorHex}`);
 
        // determining if the picture is safe to show
        const safeSearch = response.safeSearchAnnotation;
        const isSafe = ["adult", "spoof", "medical", "violence", "racy"].every(k =>
            !['LIKELY', 'VERY_LIKELY'].includes(safeSearch[k]));
        console.log(`Safe? ${isSafe}`);
 
        if (isSafe) {

            const pool = await poolPromise();
           
            

            const stmt = 'INSERT INTO sc_03_metadata_schema (labels, color, created) VALUES (?, ?, ?)';
            await pool.query(stmt, [labels, colorHex, NOW()]);
            
            console.log("Stored metadata in CloudSQL");
        }
    } else {
        throw new Error(`Vision API error: code ${response.error.code}, message: "${response.error.message}"`);
    }
};
 
 
function decColorToHex(r, g, b) {
    return '#' + Number(r).toString(16).padStart(2, '0') +
                 Number(g).toString(16).padStart(2, '0') +
                 Number(b).toString(16).padStart(2, '0');
}

The full error is as such: Error Logs