How do I change a string into a table?

So I have a string that when I print it the output is: {1, 3}. However when I try to loop through that table it outputs this error: (table expected, got string). Is there any way to change that string back into a table? I tried tonumber but it didnt work. Could someone help me out here? Thanks!

Edit 1.

local function dumpTable(tableToDump)
	local tbl = {}
	if type(tableToDump) == "table" then
		for i,v in pairs(tableToDump) do
			table.insert(tbl, tostring(v))
		end
		return "{" .. table.concat(tbl, ", ") .. "}"
	else
		return nil
	end
end

I did this because of the help of another scripting helper. Here is the link to that question. Here is the place I try to loop through the table:

local function findAMatch(savedItemsTable, item)
	
	--if type(savedItemsTable) == "table" then
		print("is a table")
		for i,v in pairs(savedItemsTable) do
	
			if v == item.ItemNumber.Value then
		
				return true
	
			else 
	
				return false
	
			end
		end

	--else
		
		--return false
		
	--end
end

certain things are commented out just because it wasnt working and I wanted to see what was wrong. The if statement if it isnt commented out will not let the code continue because the type() of savedItemsTable is a string. Hope you guys can help. Thanks!