feat: implement Erase trait for DataSourceStorage

- Add Erase trait implementation for DataSourceStorage struct
- Update set_data_sources function to use erase() instead of truncate(0)
- Provides better storage cleanup by properly erasing each field
- Matches Solidity behavior: invalidate old sources, clear storage, add new sources
- All cargo tests pass (13 passed, 0 failed)

Co-Authored-By: [email protected] <[email protected]>

Author: devin-ai-integration[bot]

target_chains/stylus/contracts/pyth-receiver/src/lib.rs

@@ -759,7 +759,7 @@ fn set_data_sources(receiver: &mut PythReceiver, data_sources: Vec<DataSource>)
         }
     }
 
-    receiver.valid_data_sources.truncate(0);
+    receiver.valid_data_sources.erase();
 
     for data_source in data_sources {
         let mut storage_data_source = receiver.valid_data_sources.grow();

target_chains/stylus/contracts/pyth-receiver/src/structs.rs

@@ -19,6 +19,13 @@ pub struct DataSourceStorage {
     pub emitter_address: StorageFixedBytes<32>,
 }
 
+impl Erase for DataSourceStorage {
+    fn erase(&mut self) {
+        self.chain_id.erase();
+        self.emitter_address.erase();
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct DataSource {
     pub chain_id: U16,