Audit unwrap() and panic sites in the explorer contract for untrusted-input paths

[priscaenoch]

Problem

explorer/src/lib.rs contains ~20 unwrap() / panic! / todo! sites. In a Soroban contract, an unhandled panic aborts the invocation and can be triggered by malformed or unexpected input, which is a poor and potentially exploitable failure mode. State-reading getters that unwrap() on absent storage (for example an uninitialised admin) will panic rather than return a typed error.

What needs to be done

• Enumerate every unwrap()/panic!/todo! in explorer/src/lib.rs.
• For each, determine whether it can be reached by untrusted input or by calling a function before init.
• Replace reachable ones with typed Error returns (Result<_, Error>) or panic_with_error! using the existing error enum, so failures are explicit and typed.
• Leave only invariant-guaranteed unwraps, each with a justifying comment.

Files

• explorer/src/lib.rs

Acceptance deliverables

• No unwrap()/panic! reachable from untrusted input without a typed error or a documented invariant.
• Calling state getters before initialisation returns a typed error rather than an untyped panic.

Tests to pass

• Tests asserting typed errors for pre-init calls and for invalid inputs on the audited functions.
• cargo test passes.

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Next steps:

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