Return EXIT_FAILURE on post-init fatal errors

It seems odd to return `EXIT_SUCCESS` when the node aborted
execution due a fatal internal error or any post-init problem
that triggers an unrequested shutdown.

e.g. blocks or coins db I/O errors, disconnect block failure,
failure during thread import (external blocks loading process
error), among others.

Co-authored-by: Ryan Ofsky <ryan@ofsky.org>

src/node/context.h

@@ -7,7 +7,9 @@
 
 #include <kernel/context.h>
 
+#include <atomic>
 #include <cassert>
+#include <cstdlib>
 #include <functional>
 #include <memory>
 #include <vector>
@@ -65,6 +67,7 @@ struct NodeContext {
     std::unique_ptr<CScheduler> scheduler;
     std::function<void()> rpc_interruption_point = [] {};
     std::unique_ptr<KernelNotifications> notifications;
+    std::atomic<int> exit_status{EXIT_SUCCESS};
 
     //! Declare default constructor and destructor that are not inline, so code
     //! instantiating the NodeContext struct doesn't need to #include class

src/node/interfaces.cpp

@@ -92,7 +92,7 @@ public:
     uint32_t getLogCategories() override { return LogInstance().GetCategoryMask(); }
     bool baseInitialize() override
     {
-        if (!AppInitBasicSetup(args())) return false;
+        if (!AppInitBasicSetup(args(), Assert(context())->exit_status)) return false;
         if (!AppInitParameterInteraction(args(), /*use_syscall_sandbox=*/false)) return false;
 
         m_context->kernel = std::make_unique<kernel::Context>();