Add line/column information consistently to every parser message.

It would be useful to have clear parser errors which have the position (line and column) printed.

Now for some errors there is information of where the error happened:

`Unterminated string literal at Line: {}, Col: {}`

For others, there isn't:

`Unexpected EOF while in a multi-line comment`

I think this would be a "good first issue" to work on, maybe I find some time to work on this soon.

首先定位 parser 错误消息，包括“Unterminated string literal”和“Unexpected EOF while in a multi-line comment”，并检查当前如何附加行和列位置。审查其余的 parser 消息，并确定覆盖这些消息的测试。当每条 parser 消息都一致地包含行和列信息时，即视为完成。

由索引模型根据 Issue 内容生成。