`recover()` method does not return a usable value when insufficient shares are provided

[diptimahamuni]

When the recover() method is called with insufficient number of shares provided (below the threshold), it should return null/falsy value. However, the recover() method currently does not return a reasonable falsy value that can be captured by the application. It also does not throw an appropriate Java Exception. Instead, the rust library crashes.

When run with the following test code:

byte[] recovered = new byte[0];
        DerecCryptoImpl cryptoImpl = new DerecCryptoImpl();

        byte[] id = "some_id".getBytes();
        byte[] secret = "top_secret".getBytes();

        List<byte[]> shares = cryptoImpl.share(id, 0, secret, 5, 3);
        ArrayList<byte[]> shares01 = new ArrayList<>();
        shares01.add(shares.get(0));
        shares01.add(shares.get(1));

        try {
            recovered = cryptoImpl.recover(id, 0, shares01);
        } catch (Exception e) {
            System.out.println("Exception occurred: " + e);
            e.printStackTrace();
        }

I get the below output after doing gradle clean build and gradle run:

> Task :run FAILED
thread '<unnamed>' panicked at <...>/cryptography/src/secret_sharing/utils.rs:45:34:
called `Result::unwrap()` on an `Err` value: Error
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':run'.
> Process 'command '/opt/homebrew/Cellar/openjdk/21.0.1/libexec/openjdk.jdk/Contents/Home/bin/java'' finished with non-zero exit value 134

* Try:
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BUILD FAILED in 454ms
6 actionable tasks: 1 executed, 5 up-to-date