Replace null, undefined, and error throwing with Effect's Option type for handling potentially missing values. This provides better type safety, composability, and prevents null reference errors. Instead of returning null: ```typescript // ❌ Avoid getBannerForEdition(edition: "app" | "btc"): BannerConfig | null { // ... } // ✅ Prefer getBannerForEdition(edition: "app" | "btc"): Option.Option { // ... } ``` Instead of using undefined: ```typescript // ❌ Avoid address = $state(undefined) // ✅ Prefer address = $state>(Option.none()) ``` Instead of throwing errors for missing values: ```typescript // ❌ Avoid export function evmDisplayToCanonical(displayAddress: string): Uint8Array { if (!/^0x[0-9a-fA-F]{40}$/.test(displayAddress)) { throw new Error("EVM address must be 0x followed by 40 hex characters") } // ... } // ✅ Prefer export function evmDisplayToCanonical(displayAddress: AddressEvmDisplay): Option.Option { // validation handled by schema, return Option for safety // ... } ``` Option provides a composable API with methods like `map`, `flatMap`, and `getOrElse` that make handling optional values more explicit and less error-prone than null checks.