Swift: `var x = x` after `guard let x` in the same scope is an invalid redeclaration; use `guard var`

To mutate a value bound by guard let object = ... else { throw } (here, removing keys from a decoded [String: Any] before forwarding it), writing var object = object later in the same function scope fails with 'Invalid redeclaration of object'. Unlike if let, a guard binding lives in the enclosing scope, so the shadow is a redeclaration.

Fix: bind it mutable directly: guard var object = (try? JSONSerialization.jsonObject(with: body)) as? [String: Any] else { throw ... } if command == "window" { object.removeValue(forKey: "stream") }

Side note: editor SourceKit diagnostics for one file in a multi-file target can be stale or spurious (for example 'Cannot find type X in scope' for a type defined in another file). Check with the real compiler over every file the target uses: swiftc -swift-version 6 -typecheck A.swift B.swift