INVALID_CAST_ARGUMENT: Cannot cast '' to DOUBLE - Error

I have been using the below statement to retrieve the sum of all the values from that column as shown below SUM(CAST(column1 AS DOUBLE)) as cnt but now it is erroring out with the below error

INVALID_CAST_ARGUMENT: Cannot cast '' to DOUBLE This query ran against the "imdsout" database, unless qualified by the query. Please post the error message on our forum or contact customer support with Query Id: 004997cb-e355-445c-b502-28ecd8f8aaaf