Improve error handling

candran.can

@@ -15,8 +15,9 @@
 local unpack = unpack or table.unpack
 
 local candran = {
-	VERSION = "0.13.0"
+	VERSION = "0.14.0"
 }
+package.loaded["candran"] = candran
 
 --- Default options.
 candran.default = {
@@ -221,7 +222,8 @@ function candran.load(chunk, chunkname, env, options={})
 	end
 
 	codeCache[options.chunkname] = code
-	local f, err = util.load(code, options.chunkname, env)
+	local f
+	f, err = util.load(code, "=%s(%s)":format(options.chunkname, "compiled candran"), env)
 
 	-- Um. Candran isn't supposed to generate invalid Lua code, so this is a major issue.
 	-- This is not going to raise an error because this is supposed to behave similarly to Lua's load function.
@@ -234,10 +236,9 @@ function candran.load(chunk, chunkname, env, options={})
 		return f
 	else
 		return function(...)
-			local params = {...}
 			if not errorRewritingActive then
 				errorRewritingActive = true
-				local t = { xpcall(() return f(unpack(params)) end, candran.messageHandler) }
+				local t = { xpcall(f, candran.messageHandler, ...) }
 				errorRewritingActive = false
 				if t[1] == false then
 					error(t[2], 0)
@@ -265,19 +266,21 @@ end
 --- Candran error message handler.
 -- Use it in xpcall to rewrite stacktraces to display Candran source file lines instead of compiled Lua lines.
 function candran.messageHandler(message)
-	return debug.traceback(message, 2):gsub("(\n?%s*)([^\n]-)%:(%d+)%:", function(indentation, source, line)
+	if not message:match("\nstack traceback:\n") then
+		message = debug.traceback(message, 2)
+	end
+	return message:gsub("(\n?%s*)([^\n]-)%:(%d+)%:", function(indentation, source, line)
 		line = tonumber(line)
 
 		local originalFile
-		local strName = source:match("%[string \"(.-)\"%]")
+		local strName = source:match("^(.-)%(compiled candran%)$")
 		if strName then
 			if codeCache[strName] then
 				originalFile = codeCache[strName]
 				source = strName
 			end
 		else
-			local fi = io.open(source, "r")
-			if fi then
+			if fi = io.open(source, "r") then
 				originalFile = fi:read("*a")
 				fi:close()
 			end
@@ -313,21 +316,31 @@ function candran.searcher(modpath)
 			return "\n\tno candran file in package.path"
 		end
 	end
-	local r, s = candran.loadfile(filepath)
-	if r then
-		return r
-	else
-		return s
-	end
+	return ()
+		local r, s = candran.loadfile(filepath)
+		if r then
+			return r()
+		else
+			error("error loading candran module '%s' from file '%s':\n\t%s":format(modpath, filepath, s), 0)
+		end
+	end, filepath
 end
 
 --- Register the Candran package searcher.
 function candran.setup()
-	if _VERSION == "Lua 5.1" then
-		table.insert(package.loaders, 2, candran.searcher)
+	local searchers = if _VERSION == "Lua 5.1" then
+		package.loaders
 	else
-		table.insert(package.searchers, 2, candran.searcher)
+		package.searchers
 	end
+	-- check if already setup
+	for _, s in ipairs(searchers) do
+		if s == candran.searcher then
+			return candran
+		end
+	end
+	-- setup
+	table.insert(searchers, 2, candran.searcher)
 	return candran
 end