fix(lsp): add more robust validation in semantic tokens

- Wrap token generation in pcall to catch any errors
- Add validation for all token parameters (line, startChar, length)
- Validate deltaStart is non-negative
- Return empty tokens if any error occurs
- This should prevent the 'Invalid line: out of range' errors

src/main.lua

@@ -563,7 +563,9 @@ function handlers.textDocument_semanticTokensFull(params)
 		return { data = {} }
 	end
 
+	-- Protected token collection
 	local tokens = {}
+	local ok, err = pcall(function()
 		local lines = {}
 		for line in doc.content:gmatch("([^\n]*)\n") do
 			table.insert(lines, line)
@@ -571,11 +573,21 @@ function handlers.textDocument_semanticTokensFull(params)
 		
 		local total_lines = #lines
 
-	local function add_token(line, startChar, length, tokenType)
+		local function add_token(line, startChar, length)
-		-- Validate line number is within bounds
+			-- Validate all parameters
+			if not line or not startChar or not length then
+				return
+			end
 			if line < 0 or line >= total_lines then
 				return
 			end
+			if startChar < 0 or length <= 0 then
+				return
+			end
+			if startChar + length > 10000 then
+				return
+			end
+			
 			local deltaLine = line
 			local deltaStart = startChar
 			if #tokens >= 4 then
@@ -587,6 +599,10 @@ function handlers.textDocument_semanticTokensFull(params)
 				else
 					deltaLine = line - prevLine
 				end
+				-- Validate deltaStart is non-negative
+				if deltaStart < 0 then
+					return
+				end
 			end
 			table.insert(tokens, deltaLine)
 			table.insert(tokens, deltaStart)
@@ -601,55 +617,38 @@ function handlers.textDocument_semanticTokensFull(params)
 
 			if doc.variables then
 				for var_name, info in pairs(doc.variables) do
-				-- Validate variable line number is within bounds
+					if info and info.line and info.line >= 0 and info.line < total_lines and info.line == lineNum then
-				if info.line and info.line >= 0 and info.line < total_lines and info.line == lineNum then
 						local startChar = line:find(var_name, 1, true)
 						if startChar then
-						add_token(lineNum, startChar - 1, #var_name, "variable")
+							add_token(lineNum, startChar - 1, #var_name)
 						end
 					end
 				end
 			end
 
 			local keywords = {
-			"IF",
+				"IF", "THEN", "ELSIF", "ELSE", "END_IF",
-			"THEN",
+				"FOR", "TO", "BY", "DO", "END_FOR",
-			"ELSIF",
+				"WHILE", "END_WHILE",
-			"ELSE",
+				"REPEAT", "UNTIL", "END_REPEAT",
-			"END_IF",
+				"CASE", "OF", "END_CASE",
-			"FOR",
+				"VAR_INPUT", "VAR_OUTPUT", "VAR_IN_OUT", "VAR_TEMP", "VAR", "END_VAR",
-			"TO",
+				"BEGIN", "EXIT", "CONTINUE", "RETURN",
-			"BY",
+				"TRUE", "FALSE",
-			"DO",
-			"END_FOR",
-			"WHILE",
-			"END_WHILE",
-			"REPEAT",
-			"UNTIL",
-			"END_REPEAT",
-			"CASE",
-			"OF",
-			"END_CASE",
-			"VAR_INPUT",
-			"VAR_OUTPUT",
-			"VAR_IN_OUT",
-			"VAR_TEMP",
-			"VAR",
-			"END_VAR",
-			"BEGIN",
-			"EXIT",
-			"CONTINUE",
-			"RETURN",
-			"TRUE",
-			"FALSE",
 			}
 			for _, kw in ipairs(keywords) do
 				local startPos = line:find("%f[%a]" .. kw .. "%f[%A]")
 				if startPos then
-				add_token(lineNum, startPos - 1, #kw, "keyword")
+					add_token(lineNum, startPos - 1, #kw)
 				end
 			end
 		end
+	end)
+	
+	-- If any error occurred, return empty tokens
+	if not ok then
+		return { data = {} }
+	end
 
 	return { data = tokens }
 end