error[E0277]: the trait bound `std::option::Option<std::string::String>: Extend<std::string::String>` is not satisfied
 --> tests/deserializer/cases/04_not_vec.rs:3:1
  |
3 | #[duplicate_keys]
  | ^^^^^^^^^^^^^^^^^ the trait `Extend<std::string::String>` is not implemented for `std::option::Option<std::string::String>`
  |
  = help: the following other types implement trait `Extend<A>`:
            `()` implements `Extend<()>`
            `(ExtendA, ExtendB)` implements `Extend<(A, B)>`
            `BTreeMap<K, V, A>` implements `Extend<(&'a K, &'a V)>`
            `BTreeMap<K, V, A>` implements `Extend<(K, V)>`
            `BTreeSet<T, A>` implements `Extend<&'a T>`
            `BTreeSet<T, A>` implements `Extend<T>`
            `BinaryHeap<T, A>` implements `Extend<&'a T>`
            `BinaryHeap<T, A>` implements `Extend<T>`
            `HashMap<K, V, S>` implements `Extend<(&'a K, &'a V)>`
            `HashMap<K, V, S>` implements `Extend<(K, V)>`
            `HashSet<T, S>` implements `Extend<&'a T>`
            `HashSet<T, S>` implements `Extend<T>`
            `LinkedList<T, A>` implements `Extend<&'a T>`
            `LinkedList<T, A>` implements `Extend<T>`
            `OsString` implements `Extend<&'a OsStr>`
            `OsString` implements `Extend<Cow<'a, OsStr>>`
            `OsString` implements `Extend<OsString>`
            `PathBuf` implements `Extend<P>`
            `Vec<T, A>` implements `Extend<&'a T>`
            `Vec<T, A>` implements `Extend<T>`
            `VecDeque<T, A>` implements `Extend<&'a T>`
            `VecDeque<T, A>` implements `Extend<T>`
            `hashbrown::map::HashMap<K, V, S, A>` implements `Extend<&'a (K, V)>`
            `hashbrown::map::HashMap<K, V, S, A>` implements `Extend<(&'a K, &'a V)>`
            `hashbrown::map::HashMap<K, V, S, A>` implements `Extend<(K, V)>`
            `hashbrown::set::HashSet<T, S, A>` implements `Extend<&'a T>`
            `hashbrown::set::HashSet<T, S, A>` implements `Extend<T>`
            `std::string::String` implements `Extend<&'a char>`
            `std::string::String` implements `Extend<&'a str>`
            `std::string::String` implements `Extend<Box<str, A>>`
            `std::string::String` implements `Extend<Cow<'a, str>>`
            `std::string::String` implements `Extend<char>`
            `std::string::String` implements `Extend<std::string::String>`
            `std::sys_common::wtf8::Wtf8Buf` implements `Extend<std::sys_common::wtf8::CodePoint>`
note: required by a bound in `<TestVisitor as Visitor<'de>>::visit_map::_::{closure#0}::assert_impl_all`
 --> tests/deserializer/cases/04_not_vec.rs:3:1
  |
3 | #[duplicate_keys]
  | ^^^^^^^^^^^^^^^^^ required by this bound in `assert_impl_all`
  = note: this error originates in the attribute macro `duplicate_keys` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0599]: no variant or associated item named `new` found for enum `std::option::Option` in the current scope
 --> tests/deserializer/cases/04_not_vec.rs:3:1
  |
3 | #[duplicate_keys]
  | ^^^^^^^^^^^^^^^^^ variant or associated item not found in `Option<_>`
  |
help: there is a method `ne` with a similar name, but with different arguments
 --> $RUST/core/src/cmp.rs
  |
  |     fn ne(&self, other: &Rhs) -> bool {
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  = note: this error originates in the attribute macro `duplicate_keys` (in Nightly builds, run with -Z macro-backtrace for more info)