Can't access enviroment variables in node.js

Serverless Framework
1

OS: darwin
Node Version: 8.11.2
Serverless Version: 1.26.0

Problem is I can’t access env variables with process.env.tableQuestions
Function returns error message:
Invalid table/index name. Table/index names must be between 3 and 255 characters long, and may contain only the characters a-z, A-Z, 0-9, ‘_’, ‘-’, and ‘.’

Here is part of serverless.yml file:
custom:
stage: {opt:stage, self:provider.stage} tableThroughputs: prod: 5 default: 1 tableThroughput: {self:custom.tableThroughputs.{self:custom.stage}, self:custom.tableThroughputs.default} webpack: webpackConfig: ./webpack.config.js includeModules: true dynamodb: start: port: 8000 inMemory: true migrate: true seed: true noStart: true seed: test: sources: - table: {env:tableQuestions}
rawsources: [./offline/seeds/questions.json]

provider:
  name: aws
  runtime: nodejs8.10
  stage: dev
  region: eu-central-1
  environment:
    tableQuestions:
      Ref: QuestionsTable
    tableReplays:
      Ref: ReplaysTable

iamRoleStatements:
  - Effect: Allow
    Action:
      - dynamodb:DescribeTable
      - dynamodb:Query
      - dynamodb:Scan
      - dynamodb:GetItem
      - dynamodb:PutItem
      - dynamodb:UpdateItem
      - dynamodb:DeleteItem
    Resource:
      - "Fn::GetAtt": [ QuestionsTable, Arn ]
      - "Fn::GetAtt": [ ReplaysTable, Arn ]

And this is my dynamoDb Resource configuration:

Resources:
    QuestionsTable:
      Type: 'AWS::DynamoDB::Table'
      DeletionPolicy: Retain
      Properties:
        AttributeDefinitions:
          - AttributeName: questionId
            AttributeType: S
        KeySchema:
          - AttributeName: questionId
            KeyType: HASH
        ProvisionedThroughput:
          ReadCapacityUnits: ${self:custom.tableThroughput}
          WriteCapacityUnits: ${self:custom.tableThroughput}
        TableName: ${self:custom.stage}-questions

    ReplaysTable:
      Type: 'AWS::DynamoDB::Table'
      DeletionPolicy: Retain
      Properties:
        AttributeDefinitions:
          - AttributeName: userId
            AttributeType: S
        KeySchema:
          - AttributeName: userId
            KeyType: HASH
        ProvisionedThroughput:
          ReadCapacityUnits: ${self:custom.tableThroughput}
          WriteCapacityUnits: ${self:custom.tableThroughput}
        TableName: ${self:custom.stage}-replays