ethereum: fix GETH_ETH_CALL_ERRORS_ENV

Previously if `GETH_ETH_CALL_ERRORS_ENV` is not set, then any error
returned from eth_call would be considered deterministic. This is
because calling `split` on an empty string returns `[""]`, not `[]`,
and all strings contain `""`. This affects release 0.24 and can
cause subgraph failures on subgraphs using contract calls,
and most severely incorrect data on subgraphs using `try_` calls.

chain/ethereum/src/ethereum_adapter.rs

@@ -111,10 +111,8 @@ lazy_static! {
     /// Additional deterministic errors that have not yet been hardcoded. Separated by `;`.
     static ref GETH_ETH_CALL_ERRORS_ENV: Vec<String> = {
         std::env::var("GRAPH_GETH_ETH_CALL_ERRORS")
-        .unwrap_or_default()
-        .split(';')
-        .map(ToOwned::to_owned)
-        .collect()
+        .map(|s| s.split(';').map(ToOwned::to_owned).collect())
+        .unwrap_or(Vec::new())
     };
 }