Lambda console is erroring on non fatal exception

Question

Hey all im running some code in the lambda console and getting the following error:

{
  "errorMessage": "'message'",
  "errorType": "KeyError",
  "requestId": "47445356-38a2-43ec-98f5-2dde22c6af1f",
  "stackTrace": [
    "  File \"/var/task/lambda_function.py\", line 11, in lambda_handler\n    dynamodb.pushPriceHistoryToDynamo(str(i.name))\n",
    "  File \"/opt/python/dynamodbPushData.py\", line 17, in pushPriceHistoryToDynamo\n    response = self.newTable.createPriceHistoryTable(tableName)\n",
    "  File \"/opt/python/createNewTable.py\", line 37, in createPriceHistoryTable\n    print(f\"[createNewTable]: {err.response['message']} Table already created\")\n"
  ]
}

This is an exception I have caught in my code on purpose however it is non-fatal and should still continue. That being said I went ahead and add a "pass" in the exception but it is still erroring out below is the code block its talking about:

    def createPriceHistoryTable(self, tableName: str) -> int:
        try:
            response = self.dynamodb.create_table(
                TableName=tableName,
                KeySchema=[
                    {
                        'AttributeName': 'date',
                        'KeyType': 'HASH'  # Hash Key
                    }
                ],
                AttributeDefinitions=[
                    {
                        'AttributeName': 'date',
                        'AttributeType': 'S'  # string data type
                    }
                ],
                ProvisionedThroughput={
                    'ReadCapacityUnits': 1,
                    'WriteCapacityUnits': 50
                }
            )
            print("[createNewTable]: New table created")
            return 200
        except ClientError  as err:
            if err.response['ResponseMetadata']['HTTPStatusCode'] == 400:
                print(f"[createNewTable]: {err.response['message']} Table already created")
            else:
                print(f"[createNewTable]: {err.response['message']}")
            pass
            return err.response['ResponseMetadata']['HTTPStatusCode']

Here is the lambda function I am actually running:

import json
import dynamodbPushData
import RegionIdEnum
import ItemIdEnum
import time

def lambda_handler(event, context):

    dynamodb = dynamodbPushData.pushData()
    for i in list(ItemIdEnum.item):
        dynamodb.pushPriceHistoryToDynamo(str(i.name))
        # dynamodb.pushItemOrdersToDynamo(str(i.name))


    
    return {
        'statusCode': 200,
        'body': json.dumps('Hello from Lambda!')
    }

Edit: Commenting out the prints and leaving the pass in does fix it. That being said I would like to log proper information for debugging. Should i use a logger instead?

except ClientError  as err:
            # if err.response['ResponseMetadata']['HTTPStatusCode'] == 400:
            #     print(f"[createNewTable]: {err.response['message']} Table already created")
            # else:
            #     print(f"[createNewTable]: {err.response['message']}")
            pass
            return err.response['ResponseMetadata']['HTTPStatusCode']
        except KeyError:
            # if err.response['ResponseMetadata']['HTTPStatusCode'] == 400:
            #     print(f"[createNewTable]: {err.response['message']} Table already created")
            # else:
            #     print(f"[createNewTable]: {err.response['message']}")
            pass
            return err.response['ResponseMetadata']['HTTPStatusCode']

Answer 1

Here's an example from the docs of the data structure that the ClientError contains:

{
    'Error': {
        'Code': 'SomeServiceException',
        'Message': 'Details/context around the exception or error'
    },
    'ResponseMetadata': {
        'RequestId': '1234567890ABCDEF',
        'HostId': 'host ID data will appear here as a hash',
        'HTTPStatusCode': 400,
        'HTTPHeaders': {'header metadata key/values will appear here'},
        'RetryAttempts': 0
    }
}

To access the error message you'd need to use:

# Message with Capital M
err.response["Error"]["Message"]

You're trying to access a non-existent key in your print statements, thus the KeyError.