refactor(jsonrpc): narrow parsing catch to JsonProcessingException

Request bodies that are not well-formed UTF-8 or that contain a NUL byte
are rejected before parsing, so the parser only sees UTF-8 input held in
memory and reports every failure as a JsonProcessingException. Go back to
catching that type. The try block still covers only the parse call.

No behavior change.

Author: waynercheung

framework/src/main/java/org/tron/core/services/jsonrpc/JsonRpcServlet.java

@@ -134,8 +134,7 @@ private void doPostInternal(HttpServletRequest req, HttpServletResponse resp) th
     JsonNode rootNode;
     try {
       rootNode = REQUEST_READER.readTree(body);
-    } catch (IOException e) {
-      // The body is already in memory, so an IOException here is a decoding failure.
+    } catch (JsonProcessingException e) {
       String message = e instanceof StreamConstraintsException
           ? e.getMessage() : "JSON parse error";
       writeJsonRpcError(resp, JsonRpcError.PARSE_ERROR, message, null, false);