algorand-typescript

Puya compiler errors usually come from using JavaScript patterns unsupported by the AVM. Replace `number` with `uint64` via `Uint64()`, remove union types like `Item | null`, and clone complex types before storage writes or array iteration.

The clone() function enforces AVM value semantics for complex types like structs and arrays. Use it when reading from GlobalState, Box, BoxMap, or LocalState, when writing structs to storage, and before iterating arrays.

BoxMap provides per-key storage without requiring user opt-in, declared as `BoxMap<Account, UserData>({ keyPrefix: 'u' })`. The app account must be funded first because each box increases the Minimum Balance Requirement.

JavaScript `number` is signed and floating-point, while the AVM requires unsigned 64-bit integers. Puya rejects `number` entirely, so declare values as `uint64` and construct them with `Uint64()`, using `biguint` for values above 2^64.

Inner transactions use lowercase methods like `itxn.payment({ ... }).submit()` from the algorand-typescript package. Always set `fee: Uint64(0)` so the outer caller covers fees through fee pooling, preventing app account drain.

No, union types like `Item | null` and `string.length` are not supported by the AVM. Use boolean flags with default-initialized values instead of nullables, and check empty strings with `text !== ''`.