Problems understanding error: `trailing characters`

[mainrs]

The error occurs on the line Apply::apply. I guess the deserializer, which takes serde_json::to_string(&Diff::serialize...) gets wrong json as input. I've uploaded the json and small code to https://github.com/SirWindfield/serde-diff-error. The error occurs on line 62:

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error("trailing characters", line: 1, column: 552)', src/main.rs:62:36
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace