fix: execution status revert reason field is optional

The Starknet JSON-RPC spec defines this field as optional.
This commit fixes compatibility with nodes like Juno that don't include
this field if the revert reason is empty.

starknet-core/src/types/execution_result.rs

@@ -61,20 +61,17 @@ impl<'de> Deserialize<'de> for ExecutionResult {
         #[cfg_attr(feature = "no_unknown_fields", serde(deny_unknown_fields))]
         struct Raw {
             execution_status: TransactionExecutionStatus,
-            revert_reason: Option<String>,
+            #[serde(default)]
+            revert_reason: String,
         }
 
         let raw = Raw::deserialize(deserializer)?;
 
-        match (raw.execution_status, raw.revert_reason) {
-            (TransactionExecutionStatus::Succeeded, None) => Ok(Self::Succeeded),
-            (TransactionExecutionStatus::Reverted, Some(reason)) => Ok(Self::Reverted { reason }),
-            (TransactionExecutionStatus::Succeeded, Some(_)) => Err(serde::de::Error::custom(
-                "field `revert_reason` must not exist when `execution_status` is `SUCCEEDED`",
-            )),
-            (TransactionExecutionStatus::Reverted, None) => Err(serde::de::Error::custom(
-                "field `revert_reason` missing when `execution_status` is `REVERTED`",
-            )),
+        match raw.execution_status {
+            TransactionExecutionStatus::Succeeded => Ok(Self::Succeeded),
+            TransactionExecutionStatus::Reverted => Ok(Self::Reverted {
+                reason: raw.revert_reason,
+            }),
         }
     }
 }