Amend rmw_init() implementation: require enclave. (#204)

Signed-off-by: Michel Hidalgo <[email protected]>

Author: hidmic

rmw_cyclonedds_cpp/src/rmw_node.cpp

@@ -1131,6 +1131,10 @@ extern "C" rmw_ret_t rmw_init(const rmw_init_options_t * options, rmw_context_t
     options->implementation_identifier,
     eclipse_cyclonedds_identifier,
     return RMW_RET_INCORRECT_RMW_IMPLEMENTATION);
+  RMW_CHECK_FOR_NULL_WITH_MSG(
+    options->enclave,
+    "expected non-null enclave",
+    return RMW_RET_INVALID_ARGUMENT);
   if (NULL != context->implementation_identifier) {
     RMW_SET_ERROR_MSG("expected a zero-initialized context");
     return RMW_RET_INVALID_ARGUMENT;