fix: json error with position

[sapphi-red]

Description

A code to show better JSON parse error existed but was not working. This PR fixes that code and adds a code to handle "Unexpected end of JSON input" error as well.

Before

[plugin:vite:json] Failed to parse JSON file, invalid JSON syntax found at line 19
D:/documents/GitHub/vite/playground/define/data.json

After

[plugin:vite:json] Failed to parse JSON file, invalid JSON syntax found at position 18
D:/documents/GitHub/vite/playground/define/data.json:2:17
1  |  {
2  |    "foo": "__EXP__
   |                  ^
3  |  }
4  |

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines, especially the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Update the corresponding documentation if needed.
• Ideally, include relevant tests that fail without this PR but pass with it.

[stackblitz]

Run & review this pull request in StackBlitz Codeflow.

[bluwy]

Nice!