Cloudformation - Route table has a conflicting association with the gateway

Question

I'm trying to deploy EC2 instance using cloudformation, It's giving the following error when i try to execute the stack.

Route table has a conflicting association with the gateway igw-0d7bbb47c8b4e8875 (Service: AmazonEC2; Status Code: 400; Error Code: RouteConflict; Request ID: 0ca161d0-b58d-4f95-a2f1-01038ccc4cae; Proxy: null)

Parameters:
  InstanceType:
    Type: "String"
    Default: t2.micro
  Image:
    Type: "String"
    Default: ami-0aab712d6363da7f9

Resources:
  WebServer:
    Type: AWS::EC2::Instance
    Properties:
      AvailabilityZone: ap-southeast-2a
      KeyName: poweruser-keypair
      InstanceType: !Ref InstanceType
      ImageId: !Ref Image
      SubnetId: !Ref SubNet
  VPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: "10.0.0.0/16"
      InstanceTenancy: default

  SubNet:
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone: ap-southeast-2a
      MapPublicIpOnLaunch: true
      CidrBlock: "10.0.0.0/24"
      VpcId: !Ref VPC

  InternetGateway:
    Type: AWS::EC2::InternetGateway

  IgwAttachment:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      InternetGatewayId: !Ref InternetGateway
      VpcId: !Ref VPC

  RouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC

  RoutingToInternet:
    Type: AWS::EC2::Route
    DependsOn: IgwAttachment
    Properties:
       RouteTableId: !Ref RouteTable
       DestinationCidrBlock: 0.0.0.0/0
       GatewayId: !Ref InternetGateway

  SubnetRouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref RouteTable
      SubnetId: !Ref SubNet

  SubnetNetworkAclAssociation:
    Type: AWS::EC2::SubnetNetworkAclAssociation
    Properties:
      SubnetId:
        Ref: SubNet
      NetworkAclId:
        Ref: NetworkACL

  NetworkACL:
    Type: AWS::EC2::NetworkAcl
    Properties:
      VpcId: !Ref VPC

  NACLEntry:
    Type: AWS::EC2::NetworkAclEntry
    Properties:
      CidrBlock: "10.0.0.0/16"
      Egress: true
      NetworkAclId: !Ref NetworkACL
      Protocol: -1
      RuleAction: "allow"
      RuleNumber: 100

Answer 1

There is nothing wrong with your cloudformation template. This means that the code that you used in the question is not fully representative of your actual template that you use.