Problem with fs-extra while deploying python using serverless

[Saeed Esmaili]

I'm not that much expert using npm and bitbucket-pipelines, but I want to create a pipeline on Bitbucket to deploy my python (flask) project using serverless to AWS Lambda. It's being deployed locally, but when I run it using the Bitbucket pipeline, this happens:

Error: Cannot find module '/opt/atlassian/pipelines/agent/build/node_modules/fs-extra/lib/index.js'. Please verify that the package.json has a valid "main" entry

Here is my code:

bitbucket-pipelines.yml

image: node:14.13.1-alpine3.10

pipelines:
  branches:
    master:
      - step:
          caches:
            - node
          script:
            - apk add python3
            - npm install
            - npm install -g serverless
            - serverless config credentials --stage dev --provider aws --key ${AWS_DEV_LAMBDA_KEY} --secret ${AWS_DEV_LAMBDA_SECRET}
            - serverless deploy --stage dev

serverless.yml

service: serverless-flask

plugins:
  - serverless-python-requirements
  - serverless-wsgi

custom:
  wsgi:
    app: app.app
    packRequirements: false
  pythonRequirements:
    dockerizePip: non-linux

provider:
  name: aws
  runtime: python3.8
  stage: dev
  region: us-west-2

functions:
  app:
    handler: wsgi.handler
    events:
      - http: ANY /
      - http: 'ANY {proxy+}'
  alert:
    handler: alerts.run
    events:
      - schedule: rate(1 day)

package:
    exclude:
      - .venv/**
      - venv/**
      - node_modules/**
      - bitbucket-pipelines.yml

How can I fix this?