Google Sheets: Those rows are out of bounds error - google-apps-script

Question

I am brand new to writing code and I am fumbling through this trying to come up with a spreadsheet that is fed info from a form. I have searched and searched for the answer to this problem for days but I cannot figure it out on my own without some help..so HELP! :)
What my script does it creates a copy of a sheet based on a trigger every night so that I have a record of form responses for each day. I want to to delete (not clear) all rows except the top 6 rows each time a new sheet is created so the form will add lines each time a response is given. I keep getting the Those rows are out of bounds. (line 17, file "DailyClear") when I try to run the script.
Here is what I've got
function dailyclear(e)
{
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getSheetByName('Today');
sheet.copyTo(ss)
var nusheet = ss.getSheetByName('Copy of Today')
var value = nusheet.getRange("B2").getCell(1,1).getValue()
SpreadsheetApp.setActiveSheet(nusheet)
Logger.log("Current index of sheet: %s", nusheet.getIndex())
ss.moveActiveSheet(2);
nusheet.setName(value);
//Clear "Today"
var lastrow = sheet.getLastRow()
sheet.deleteRows(7, lastrow-6)
//Set Date Value for "Today"
var dd = Utilities.formatDate(new Date(), "GMT-5", "MM/dd/yy");
sheet.getRange("B2").getCell(1,1).setValue(dd);
}
It will not allow me to delete the 7th row and retain rows 1-6 without throwing that error if the 7th row is blank and the only row that exists. If I start adding information from form responses in the cells and it starts creating rows and I run the script it throws up the error Sorry, it is not possible to delete all non-frozen rows. (line 17, file "DailyClear"). And on top of all that when a new sheet is created I have the 7th row clear ready for the first response from the form to fill and the form puts the first response of the day on row 8 and leaves 7 blank! This is driving me crazy...anyone recommend a good book for beginners before I go crazy? :( Thanks for any help I can get, here is a link to my sheet..
https://docs.google.com/spreadsheets/d/1NZxXjMptx6ldzL2CKk6OwJcq_heIv995ZGVeIE59xNc/edit?usp=sharing
Thank you to anyone who can help

Answer 1

As noted already, you cannot delete all non-frozen rows, so Row 7 will have to stay. Perhaps shrink it down and add a fill or some formatting so it just doesn't look like an empty row, and then since data is entered on row 8 anyway, change your script slightly to accomodate:
function dailyclear(e)
{
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getSheetByName('Today');
sheet.copyTo(ss)
var nusheet = ss.getSheetByName('Copy of Today')
var value = nusheet.getRange("B2").getCell(1,1).getValue()
SpreadsheetApp.setActiveSheet(nusheet)
Logger.log("Current index of sheet: %s", nusheet.getIndex())
ss.moveActiveSheet(2);
nusheet.setName(value);
//Clear "Today"
var lastrow = sheet.getLastRow()
sheet.deleteRows(8, lastrow-7);
//Set Date Value for "Today"
var dd = Utilities.formatDate(new Date(), "GMT-5", "MM/dd/yy");
sheet.getRange("B2").getCell(1,1).setValue(dd);
}