check the exception to unexpected responses from the server.

mdrsclient/__main__.py

@@ -1,5 +1,6 @@
 import argparse
 import sys
+from json import JSONDecodeError
 
 from mdrsclient.commands import (
     ChaclCommand,
@@ -52,6 +53,9 @@ def main() -> None:
     except MDRSException as e:
         print(f"Error: {e}")
         sys.exit(2)
+    except JSONDecodeError:
+        print("Unexpected response returned. Please check the configuration or the server's operational status.")
+        sys.exit(2)
     except KeyboardInterrupt:
         sys.exit(130)