NPL  lexer error

There is an error when compiling *.npl file, please fix it. 

```
[string "script/ide/System/Compiler/lib/lexer.lua"]:366: attempt to index local 'a' (a nil value) <Runtime error>
2017-07-23 3:43:48 PM 799872312|main|error|npl_page_parser|<Runtime error>: [string "script/ide/System/Compiler/lib/lexer.lua"]:366: attempt to index local 'a' (a nil value) in 
```