start working on implementing some kind of system to catch error messages

....it works, but:
- We can't capture stack traces like this
- It's messy
- We need to implement an escape/encodeURIComponent function ourselves from scratch 'cause the one I ripped from Stack Overflow sucks

worldeditadditions_core/core/run_command.lua

@@ -8,7 +8,7 @@ local human_size = wea_c.format.human_size
 
 -- TODO: Reimplement worldedit.player_notify(player_name, msg_text)
 
---- Actually runs the command in question.
+--- Actually runs the command in question. [HIDDEN]
 -- Unfortunately needed to keep the codebase clena because Lua sucks.
 -- @internal
 -- @param	player_name	string		The name of the player executing the function. 
@@ -34,6 +34,51 @@ local function run_command_stage2(player_name, func, parse_result, tbl_event)
 	wea_c:emit("post-execute", tbl_event)
 end
 
+local function send_error(player_name, cmdname, msg, stack_trace)
+	print("DEBUG:HAI SEND_ERROR")
+	local msg_compiled = table.concat({
+		"[//", cmdname, "] Error: ",
+		msg,
+		"\n",
+		"Please report this by opening an issue on GitHub! Bug report link:\n",
+		"https://github.com/sbrl/Minetest-WorldEditAdditions/issues/new?title=",
+		wea_c.format.escape(stack_trace:match("^[^\n]+")), -- extract 1st line & escape
+		"&body=",
+		wea_c.format.escape([[## Describe the bug
+What's the bug? Be clear and detailed but concise in our explanation. Don't forget to include any context, error messages, logs, and screenshots required to understand the issue if applicable.
+
+## Reproduction steps
+Steps to reproduce the behaviour:
+1. Go to '...'
+2. Click on '....'
+3. Enter this command to '....'
+4. See error
+
+## System information (please complete the following information)
+- **Operating system and version:** [e.g. iOS]
+- **Minetest version:** [e.g. 5.8.0]
+- **WorldEdit version:**
+- **WorldEditAdditions version:**
+
+Please add any other additional specific system information here too if you think it would help.
+
+## Stack trace
+- Command name: ]]),
+		wea_c.format.escape(cmdname),
+		wea_c.format.escape("```\n"),
+		wea_c.format.escape(stack_trace),
+		wea_c.format.escape("\n```"),
+		"-------------------------------------\n",
+		"*** Stack trace ***\n",
+		stack_trace,
+		"\n",
+		"-------------------------------------"
+	}, "")
+	
+	print("DEBUG:player_notify player_name", player_name, "msg_compiled", msg_compiled)
+	worldedit.player_notify(player_name, msg_compiled)
+end
+
 --- Command execution pipeline: before `paramtext` parsing but after validation.
 -- 
 -- See `worldeditadditions_core.run_command`
@@ -112,7 +157,22 @@ local function run_command(cmdname, options, player_name, paramtext)
 	
 	wea_c:emit("pre-parse", tbl_event)
 	
-	local parse_result = { options.parse(paramtext) }
+	local parse_result, error_message
+	local did_error = false
+	xpcall(function()
+		parse_result = { options.parse(paramtext)}
+	end, function(error_raw)
+		did_error = true
+		error_message = error_raw
+		print("DEBUG:parse_result>>error", error_raw, "stack trace", debug.traceback())
+	end)
+	if did_error then
+		print("DEBUG:parse_result EXIT_DUE_TO_ERROR")
+		send_error(player_name, cmdname, "The command crashed when parsing the arguments.", error_message)
+		print("DEBUG:parse_result EXIT_DUE_TO_ERROR __final_call__")
+		return false
+	end -- handling is wrapped with xpcall()
+	
 	local success = table.remove(parse_result, 1)
 	if not success then
 		worldedit.player_notify(player_name, ("[//"..tostring(cmdname).."] "..tostring(parse_result[1])) or "Invalid usage (no further error message was provided by the command. This is probably a bug.)")

worldeditadditions_core/init.lua

@@ -11,14 +11,33 @@ local modpath = minetest.get_modpath("worldeditadditions_core")
 
 local EventEmitter = dofile(modpath .. "/utils/EventEmitter.lua")
 
+local directory_separator = "/"
+if package and package.config then
+	directory_separator = package.config:sub(1,1)
+end
+
 worldeditadditions_core = EventEmitter.new({
 	version = "1.15-dev",
+	--- The directory separator on the current host system
+	-- @value string
+	dirsep = directory_separator,
+	--- The full absolute filepath to the mod worldeditadditions_core
+	-- @value 
 	modpath = modpath,
+	--- The full absolute filepath to the data directory WorldEditAdditions can store miscellaneous data in.
+	-- @value
+	datapath = minetest.get_worldpath() .. directory_separator .."worldeditadditions",
+	--- A table containing the definitions for all commands registered in WorldEditAdditions.
+	-- Keys are the command name SANS any forward slashes! So //replacemix would be registered as simply replacemix.
+	-- @value table<string, table>
 	registered_commands = {},
-	-- Storage for per-player node limits before safe_region kicks in.
+	--- Storage for per-player node limits before safe_region kicks in.
 	-- TODO: Persist these to disk.
+	-- @value table<string, number>
 	safe_region_limits = {},
-	-- The default limit for new players on the number of potential nodes changed before safe_region kicks in.
+	--- The default limit for new players on the number of potential nodes changed before safe_region kicks in.
+	-- TODO make this configurable
+	-- @value number
 	safe_region_limit_default = 100000,
 })
 local wea_c = worldeditadditions_core

worldeditadditions_core/utils/format/escape.lua

@@ -0,0 +1,18 @@
+--- 
+-- @module worldeditadditions_core
+
+-- decodeURIComponent() implementation
+-- Ref https://stackoverflow.com/a/78225561/1460422
+
+-- TODO this doesn't work. It replaces \n with %A instead of %0A, though we don't know if that's a problem or not
+-- it also doesn't handle quotes even though we've clearly got them in the Lua pattern
+local function _escape_char(char)
+	print("_escape_char char", char, "result", string.format('%%%0X', string.byte(char)))
+	return string.format('%%%0X', string.byte(char))
+end
+
+local function escape(uri)
+	return (string.gsub(uri, "[^%a%d%-_%.!~%*'%(%);/%?:@&=%+%$,#]", _escape_char))
+end
+
+return escape

worldeditadditions_core/utils/format/init.lua

@@ -8,5 +8,6 @@ wea_c.format = {
 	node_distribution = dofile(wea_c.modpath.."/utils/format/node_distribution.lua"),
 	make_ascii_table = dofile(wea_c.modpath.."/utils/format/make_ascii_table.lua"),
 	map = dofile(wea_c.modpath.."/utils/format/map.lua"),
+	escape = dofile(wea_c.modpath.."/utils/format/escape.lua")
 }
 

worldeditadditions_core/utils/setting_handler.lua

@@ -4,10 +4,10 @@ local wea_c = worldeditadditions_core
 wea_c.settings = {}
 
 -- Initialize wea world folder if not already existing
-local path = minetest.get_worldpath() .. "/worldeditadditions"
+local path = minetest.get_worldpath() .. wea_c.dirsep .. "worldeditadditions"
 minetest.mkdir(path)
 
---- A wrapper to simultaniously handle global and world settings.
+--- A wrapper to simultaneously handle global and world settings.
 -- @namespace worldeditadditions_core.setting_handler
 local setting_handler = {}