Finalize fails with json.decoder.JSONDecodeError: Expecting ',' delimiter

I can't seem to compile my Rust-based application on the latest emscripten (tried 2.0.23 and 2.0.22). Seems like wasm-emscripten-finalize is spitting out invalid JSON:

```
json.decoder.JSONDecodeError: Expecting ',' delimiter: line 30 column 22 (char 9178)
```

The bad line appears to be here, where unescaped quote marks are being inserted:

```
"__invoke_void_%"std::vec::Vec>"*",
```

I'm assuming that wasm-emscripten-finalize would just need to look for quote marks in these names and replace them with `\"`? Or should the quote marks not be there at all?

Full error log attached.
[emscripten_error.txt](https://github.com/emscripten-core/emscripten/files/6604693/emscripten_error.txt)