meson generated json files does not pass standard json validation test

**Describe the bug**
[OpenBMC project](https://github.com/openbmc) uses [eslint-json-validation](https://www.npmjs.com/package/eslint-plugin-json) plugin for json files validation in our repository CI ,and we found that meson build generated JSON files do not pass the JSON validation test.

These are the validation errors that we see :
```
build/meson-logs/testlog-ubasan.json
2:2 error End of file expected json/*

build/meson-logs/testlog-valgrind.json
2:2 error End of file expected json/*

build/meson-logs/testlog.json
2:2 error End of file expected json/*
```
It would be great , if meson can fix those.

Reproduce the validation failure against build/meson-logs/testlog.json, testlog-ubasan.json, and testlog-valgrind.json, then trace the Meson path that generates these logs. Done means the generated files pass the standard JSON validation test without the reported End of file expected errors.

Written by the indexing model from the issue text.