Fix: peek panics

[TilakMaddy]

Sometimes for node properties offset, len can have values like -1

That's why it's important we check the bounds before we return the string

Fix for #369

[alexroan]

Waiting for Hackathon submissions to conclude before addressing this PR 👍

[alexroan]

Could you add tests to check for these negative values please @TilakMaddy ?

Any time we fix something that's breaking, we should introduce tests at the same time :)

[TilakMaddy]

I made a mistake in PR readme. I don't think it's because of negative values (because we are deserializing it to usize). It has to be something else. Let me re run this without the checks on https://github.com/smartcontractkit/ccip/tree/ccip-develop/contracts to find out what values they were (which causes index out of bounds panic)

[alexroan]

@TilakMaddy is this still relevant ?

[TilakMaddy]

@TilakMaddy is this still relevant ?

Yes Alex, we should get this PR in because it's important to check that index lies within bounds before accessing array element at that index