fix: rust 1.42.0 errors

Author: samparsky

adapter/src/ethereum.rs

@@ -490,7 +490,7 @@ mod test {
         let sig1 = "0x9fa5852041b9818021323aff8260624fd6998c52c95d9ad5036e0db6f2bf2b2d48a188ec1d638581ff56b0a2ecceca6d3880fc65030558bd8f68b154e7ebf80f1b";
         let msg = "1648231285e69677531ffe70719f67a07f3d4393b8425a5a1c84b0c72434c77b";
 
-        let verify2 = eth_adapter
+        let _verify2 = eth_adapter
             .verify(
                 &ValidatorId::try_from("ce07CbB7e054514D590a0262C93070D838bFBA2e")
                     .expect("Failed to parse id"),

primitives/src/big_num.rs

@@ -1,5 +1,4 @@
 use std::convert::TryFrom;
-use std::error::Error;
 use std::iter::Sum;
 use std::ops::{Add, AddAssign, Div, Mul, Sub};
 use std::str::FromStr;
@@ -195,7 +194,7 @@ impl TryFrom<&str> for BigNum {
 
     fn try_from(num: &str) -> Result<Self, Self::Error> {
         let big_uint = BigUint::from_str(&num)
-            .map_err(|err| super::DomainError::InvalidArgument(err.description().to_string()))?;
+            .map_err(|err| super::DomainError::InvalidArgument(err.to_string()))?;
 
         Ok(Self(big_uint))
     }