Duplicate ids causes panic

[serega]

The code results in panic.

#[test]
pub fn test_duplidate_ids() {
    let (b, r) = calculate_minhash_params(0.5, 200);
    let min_hash = MinHasher64V1::new(b * r);
    let mut lsh_index = MinHashIndex::new(b, r, 0.5);
    lsh_index.insert(1, min_hash.create_signature(S1.split_whitespace()));
    lsh_index.insert(1, min_hash.create_signature(S4.split_whitespace()));
    lsh_index.insert(6, min_hash.create_signature(S6.split_whitespace()));
    
    println!("{}", lsh_index);
    assert_eq!(lsh_index.size(), 2);
    lsh_index.remove(&1);
    let ret = lsh_index.query(&min_hash.create_signature(S1.split_whitespace()));
    println!("{:?}", ret);
}

no entry found for key
thread 'minhash::minhash_index::tests::test_duplidate_ids' panicked at 'no entry found for key', gaoya/src/minhash/minhash_index.rs:552:30
stack backtrace:
   0: rust_begin_unwind
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/std/src/panicking.rs:575:5
   1: core::panicking::panic_fmt
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/panicking.rs:64:14
   2: core::panicking::panic_display
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/panicking.rs:147:5
   3: core::panicking::panic_str
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/panicking.rs:131:5
   4: core::option::expect_failed
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/option.rs:1924:5
   5: core::option::Option<T>::expect
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/option.rs:786:21
   6: <std::collections::hash::map::HashMap<K,V,S> as core::ops::index::Index<&Q>>::index
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/std/src/collections/hash/map.rs:1340:23
   7: gaoya::minhash::minhash_index::MinHashIndex<T,Id,C>::query::{{closure}}
             at ./src/minhash/minhash_index.rs:552:30
   8: hashbrown::set::HashSet<T,S,A>::retain::{{closure}}
             at /Users/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.12.3/src/set.rs:325:32
   9: hashbrown::map::HashMap<K,V,S,A>::retain
             at /Users/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.12.3/src/map.rs:834:21
  10: hashbrown::set::HashSet<T,S,A>::retain
             at /Users/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.12.3/src/set.rs:325:9
  11: std::collections::hash::set::HashSet<T,S>::retain
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/std/src/collections/hash/set.rs:333:9
  12: gaoya::minhash::minhash_index::MinHashIndex<T,Id,C>::query
             at ./src/minhash/minhash_index.rs:551:9
  13: gaoya::minhash::minhash_index::tests::test_duplidate_ids
             at ./src/minhash/minhash_index.rs:1208:19
  14: gaoya::minhash::minhash_index::tests::test_duplidate_ids::{{closure}}
             at ./src/minhash/minhash_index.rs:1197:33
  15: core::ops::function::FnOnce::call_once
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/ops/function.rs:250:5
  16: core::ops::function::FnOnce::call_once
             at /rustc/9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.```

The current logic does not check in the `insert` method whether ID is already present in the index. The assumption is that IDs are unique and it is up to the caller to handle duplicates.

[serega]

Fixed by #20