Fix lua error in toChar and toUnicodeChar (#3310)

Author: Astralcircle

lua/entities/gmod_wire_expression2/core/string.lua

@@ -120,7 +120,7 @@ local utf8_byte = utf8.codepoint
 __e2setcost(1)
 
 e2function string toChar(number n)
-	if n < 0 or n > 255 then return self:throw("Invalid argument (" .. n .. ") (must be between 0 and 255)", "") end
+	if n ~= n or n < 0 or n > 255 then return self:throw("Invalid argument (" .. n .. ") (must not be NaN and be between 0 and 255)", "") end
 	return string_char(n)
 end
 
@@ -139,7 +139,7 @@ local math_floor = math.floor
 e2function string toUnicodeChar(number byte)
 	-- upper limit used to be 2097152, new limit acquired using pcall and a for loop
 	-- above this limit, the function causes a lua error
-	if byte < 1 or byte > 1114112 then return self:throw("Invalid argument (" .. byte .. ") (must be between 1 and 1,114,112)", "") end
+	if byte ~= byte or byte < 1 or byte > 1114112 then return self:throw("Invalid argument (" .. byte .. ") (must not be NaN and be between 1 and 1,114,112)", "") end
 	return utf8_char(byte)
 end