# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1689002345 -7200
# Node ID c48ae06e24d6d2070abd2a852662af27c0045f4b
# Parent  87487056bccb06894de85adb407578834acc4dc1
util.datamanager: Fix indexing first item if not at the very start

If the first item does not start at position 0 then the index function
produces a phantom first entry covering position zero until where the
real first item starts. When using the index, this would make it either
appear as the first item was missing or cause an off-by-one issue with
remaining items.

diff -r 87487056bccb -r c48ae06e24d6 util/datamanager.lua
--- a/util/datamanager.lua	Wed Jul 12 10:24:28 2023 +0200
+++ b/util/datamanager.lua	Mon Jul 10 17:19:05 2023 +0200
@@ -329,7 +329,7 @@
 		return fh, err, errno;
 	end
 	local prev_pos = 0; -- position before reading
-	local last_item_start = 0;
+	local last_item_start = nil;
 
 	if items and items[1] then
 		local last_item = items[#items];
@@ -340,7 +340,7 @@
 
 	for line in fh:lines() do
 		if line:sub(1, 4) == "item" then
-			if prev_pos ~= 0 then
+			if prev_pos ~= 0 and last_item_start then
 				t_insert(items, { start = last_item_start; length = prev_pos - last_item_start });
 			end
 			last_item_start = prev_pos