No token params in ownerAPI creates a panic

[quentinlesceller]

Tested on Floonet and Mainnet.

Updated: the panic happens when the token is not provided.

Error log:

20200616 12:28:21.825 ERROR grin_util::logger -
thread 'tokio-runtime-worker' panicked at 'index 32 out of range for slice of length 0': /Users/quentin/.cargo/git/checkouts/grin-b002917b6a725898/dd88d28/core/src/libtx/secp_ser.rs:129   0: backtrace::backtrace::trace
   1: backtrace::capture::Backtrace::new
   2: grin_util::logger::send_panic_to_log::{{closure}}
   3: std::panicking::rust_panic_with_hook
   4: _rust_begin_unwind
   5: core::panicking::panic_fmt
   6: core::slice::slice_index_len_fail
   7: grin_core::libtx::secp_ser::option_seckey_serde::deserialize
   8: <dyn grin_wallet_api::owner_rpc::OwnerRpc as easy_jsonrpc_mw::Handler>::handle
   9: easy_jsonrpc_mw::handle_call
  10: easy_jsonrpc_mw::handle_parsed_request
  11: easy_jsonrpc_mw::Handler::handle_request
  12: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
  13: <hyper::proto::h1::dispatch::Server<S,hyper::body::body::Body> as hyper::proto::h1::dispatch::Dispatch>::poll_msg
  14: hyper::proto::h1::dispatch::Dispatcher<D,Bs,I,T>::poll_catch
  15: <hyper::server::conn::upgrades::UpgradeableConnection<I,S,E> as core::future::future::Future>::poll
  16: <hyper::server::conn::spawn_all::NewSvcTask<I,N,S,E,W> as core::future::future::Future>::poll
  17: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  18: tokio::runtime::task::harness::Harness<T,S>::poll
  19: std::thread::local::LocalKey<T>::with
  20: tokio::runtime::thread_pool::worker::Context::run_task
  21: tokio::runtime::thread_pool::worker::Context::run
  22: tokio::macros::scoped_tls::ScopedKey<T>::set
  23: tokio::runtime::thread_pool::worker::run
  24: tokio::loom::std::unsafe_cell::UnsafeCell<T>::with_mut
  25: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  26: tokio::runtime::task::harness::Harness<T,S>::poll
  27: tokio::runtime::blocking::pool::Inner::run
  28: tokio::runtime::context::enter
  29: std::sys_common::backtrace::__rust_begin_short_backtrace
  30: core::ops::function::FnOnce::call_once{{vtable.shim}}
  31: std::sys::unix::thread::Thread::new::thread_start
  32: __pthread_start



Thread 'tokio-runtime-worker' panicked with message:
"index 32 out of range for slice of length 0"
See /Users/quentin/.grin/main/grin-wallet.log for further details.