Bug: Identifier:score {operation} doesn't work

[PokeJofeJr4th]

Describe the bug A clear and concise description of what the bug is.

To Reproduce Steps to reproduce the behavior: Enter this minescript source:

enemy:score += 10

Here's the output from an end-to-end test

---- tests::e2e::variables stdout ----
thread 'tests::e2e::variables' panicked at 'called `Result::unwrap()` on an `Err` value: "Unexpected item `{\"enemy\": Ident(\"score\") += 10}`"', src\tests\e2e.rs:69:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

failures:
    tests::e2e::variables

test result: FAILED. 22 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.03s

error: test failed, to rerun pass `--bin minescript`

Expected behavior

identifier:score += 10

should compile to

scoreboard players add %identifier score 10