Fix lints introduced in Rust 1.35

validator_client/src/error.rs

@@ -1,9 +1,6 @@
 use slot_clock;
 
-use error_chain::{
-    error_chain, error_chain_processing, impl_error_chain_kind, impl_error_chain_processed,
-    impl_extract_backtrace,
-};
+use error_chain::error_chain;
 
 error_chain! {
    links  { }