EF Core: Issue with creating FUNCTION in Ef Core Migration

I can't seem to figure out why this error is occurring?Error SQL80001: Incorrect syntax: 'CREATE FUNCTION' must be the only statement in the batch. Miscellaneous Files 

IF NOT EXISTS(SELECT * FROM [DataTools].[_EFMigrationsHistory] WHERE [MigrationId] = N'20200718013559_CreateCombineResourcesFuncForScheduler07172020')
BEGIN
    drop function if exists [dbo].[GetCombinedResources]
END;

GO

IF NOT EXISTS(SELECT * FROM [DataTools].[_EFMigrationsHistory] WHERE [MigrationId] = N'20200718013559_CreateCombineResourcesFuncForScheduler07172020')
BEGIN

                            // ERROR IS RIGHT HERE

                            Create FUNCTION dbo.GetCombinedResources
                            (@resourceTypeName VARCHAR(max),
                            @scheduleId INT,
                            @scheduleEventId INT)
                            RETURNS VARCHAR(max)
                            AS
                            BEGIN													  
                            declare @result varchar(500)
                            set @result = ''

I have not checked it into VSTS yet. I see this error when I complete:

PM> script-migration -i

Here is my migration:

        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.Sql(@"drop function if exists [dbo].[GetCombinedResources]");

            migrationBuilder.Sql(@"
                        Create FUNCTION dbo.GetCombinedResources
                        (@resourceTypeName VARCHAR(max),
                        @scheduleId INT,
                        @scheduleEventId INT)
                        RETURNS VARCHAR(max)
                        AS
                        BEGIN													  
                        declare @result varchar(500)
                        set @result = ''

                        select @result = @result + query.Name + ', ' from
                        (
                        SELECT distinct Resources.Name   FROM 
Events INNER JOIN Schedules ON Events.ScheduleId = ScheduleId and ScheduleEventId = @scheduleEventId
                        ) query

                        if (@result is null or @result = '')
	                        BEGIN
		                        return null	
	                        END
	
	                    return LEFT(@result, NULLIF(LEN(@result)-1,-1))		
                    END
                  
            ");
        }