AP_Scripting: add init failure check

libraries/AP_Scripting/AP_Scripting.cpp

@@ -87,7 +87,7 @@ bool AP_Scripting::init(void) {
     if (!hal.scheduler->thread_create(FUNCTOR_BIND_MEMBER(&AP_Scripting::thread, void),
                                       "Scripting", SCRIPTING_STACK_SIZE, AP_HAL::Scheduler::PRIORITY_SCRIPTING, 0)) {
         gcs().send_text(MAV_SEVERITY_CRITICAL, "Could not create scripting stack (%d)", SCRIPTING_STACK_SIZE);
-        _enable = 0;
+        _init_failed = true;
         return false;
     }
 
@@ -96,8 +96,9 @@ bool AP_Scripting::init(void) {
 
 void AP_Scripting::thread(void) {
     lua_scripts *lua = new lua_scripts(_script_vm_exec_count, _script_heap_size, _debug_level);
-    if (lua == nullptr) {
+    if (lua == nullptr || !lua->heap_allocated()) {
         gcs().send_text(MAV_SEVERITY_CRITICAL, "Unable to allocate scripting memory");
+        _init_failed = true;
         return;
     }
     lua->run();

libraries/AP_Scripting/AP_Scripting.h

@@ -29,6 +29,7 @@ public:
     AP_Scripting &operator=(const AP_Scripting&) = delete;
 
     bool init(void);
+    bool init_failed(void) const { return _init_failed; }
 
     bool enabled(void) const { return _enable != 0; };
 
@@ -46,6 +47,8 @@ private:
     AP_Int32 _script_heap_size;
     AP_Int8 _debug_level;
 
+    bool _init_failed;  // true if memory allocation failed
+
     static AP_Scripting *_singleton;
 
 };

libraries/AP_Scripting/lua_scripts.h

@@ -30,6 +30,9 @@ public:
     lua_scripts(const lua_scripts &other) = delete;
     lua_scripts &operator=(const lua_scripts&) = delete;
 
+    // return true if initialisation failed
+    bool heap_allocated() const { return _heap != nullptr; }
+
     // run scripts, does not return unless an error occured
     void run(void);