[#609] morph/client: Check return state in invoke

Test invocations are used in `Invoke` method to calculate
consumed gas. We can check return code and return error
if panic happened in contract.

This is already done the same way in `TestInvoke` method.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/morph/client/client.go

@@ -100,6 +100,10 @@ func (c *Client) Invoke(contract util.Uint160, fee fixedn.Fixed8, method string,
 		return err
 	}
 
+	if resp.State != HaltState {
+		return &NotHaltStateError{state: resp.State, exception: resp.FaultException}
+	}
+
 	if len(resp.Script) == 0 {
 		return errEmptyInvocationScript
 	}