fix(rpc): Always set data on JSONRPCError, even if None (#2301)

Author: kclowes

src/ethereum_test_rpc/rpc_types.py

@@ -40,12 +40,11 @@ def __init__(self, code: int | str, message: str, data: str | None = None) -> No
         """Initialize the JSONRPCError."""
         self.code = int(code)
         self.message = message
-        if data:
-            self.data = data
+        self.data = data
 
     def __str__(self) -> str:
         """Return string representation of the JSONRPCError."""
-        if self.data:
+        if self.data is not None:
             return f"JSONRPCError(code={self.code}, message={self.message}, data={self.data})"
 
         return f"JSONRPCError(code={self.code}, message={self.message})"