Fix compilation error

rust/coverage.stats

@@ -1 +1 @@
-91.5
+92.0

rust/tw_coin_entry/src/coin_entry.rs

@@ -74,21 +74,15 @@ pub trait CoinEntry {
 
     /// It is optional, Signing JSON input with private key.
     /// Returns `Ok(None)` if the chain doesn't support signing JSON.
-    fn json_signer(&self) -> Option<Self::JsonSigner> {
-        None
-    }
+    fn json_signer(&self) -> Option<Self::JsonSigner>;
 
     /// Planning, for UTXO chains, in preparation for signing.
     /// Returns an optional `Plan` builder. Only UTXO chains need it.
-    fn plan_builder(&self) -> Option<Self::PlanBuilder> {
-        None
-    }
+    fn plan_builder(&self) -> Option<Self::PlanBuilder>;
 
     /// Optional helper to prepare a `SigningInput` from simple parameters.
     /// Not suitable for UTXO chains.
     ///
     /// Returns `None` if the chain doesn't support creating `SigningInput` from the simple parameters.
-    fn signing_input_builder(&self) -> Option<Self::InputBuilder> {
-        None
-    }
+    fn signing_input_builder(&self) -> Option<Self::InputBuilder>;
 }

rust/tw_ethereum/src/entry.rs

@@ -82,6 +82,10 @@ impl CoinEntry for EthereumEntry {
         Some(EthJsonSigner)
     }
 
+    fn plan_builder(&self) -> Option<Self::PlanBuilder> {
+        None
+    }
+
     fn signing_input_builder(&self) -> Option<Self::InputBuilder> {
         Some(EthInputBuilder)
     }

src/rust/Wrapper.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <memory>
 #include <optional>
 
 #include "../Data.h"