feat(abigen): descriptive deserialization errors (#1633)

* feat(abigen): descriptive deserialization errors

* update changelog

* map_err -> wrap_err

CHANGELOG.md

@@ -104,6 +104,8 @@
   `my_contract` rather than `mycontract_mod`.
 - The `Cargo.toml` generated by bindings now includes the `abigen` feature on
   ethers. [#1508](https://github.com/gakonst/ethers-rs/pull/1508)
+- More descriptive contract deserialization errors.
+  [#1633](https://github.com/gakonst/ethers-rs/pull/1633)
 
 ### 0.6.0
 

ethers-contract/ethers-contract-abigen/src/contract.rs

@@ -191,7 +191,9 @@ impl Context {
         // holds the bytecode parsed from the abi_str, if present
         let mut contract_bytecode = None;
 
-        let (abi, human_readable, abi_parser) = parse_abi(&abi_str)?;
+        let (abi, human_readable, abi_parser) = parse_abi(&abi_str).wrap_err_with(|| {
+            eyre::eyre!("error parsing abi for contract: {}", args.contract_name)
+        })?;
 
         // try to extract all the solidity structs from the normal JSON ABI
         // we need to parse the json abi again because we need the internalType fields which are
@@ -351,7 +353,8 @@ fn parse_abi(abi_str: &str) -> Result<(Abi, bool, AbiParser)> {
         (abi, true, abi_parser)
     } else {
         // a best-effort coercion of an ABI or an artifact JSON into an artifact JSON.
-        let contract: JsonContract = serde_json::from_str(abi_str)?;
+        let contract: JsonContract = serde_json::from_str(abi_str)
+            .wrap_err_with(|| eyre::eyre!("failed deserializing abi:\n{}", abi_str))?;
 
         (contract.into_abi(), false, abi_parser)
     };