Error and warn functions contd.

* Mark things `static` and `const` as appropriate
* Move “level wasn’t set up” warning to the central method
* Inline `err` as the errno returns are unused for beïng cryptic

src/cleanup.c

@@ -1,23 +1,22 @@
 #include "cleanup.h"
 
-void godot_rb_cleanup_core() {
-  if(godot_rb_init_levels[GDEXTENSION_INITIALIZATION_CORE]) {
-    int err = ruby_cleanup(EXIT_SUCCESS);
-    if(err)
-      godot_rb_error("Ruby ran into a problem while exiting.", __func__, __FILE__, __LINE__);
-  } else
-    godot_rb_warn("Godot.rb hasn't set this init level up.", __func__, __FILE__, __LINE__);
+static void godot_rb_cleanup_core() {
+  if(ruby_cleanup(EXIT_SUCCESS))
+    godot_rb_error("Ruby ran into a problem while exiting.", __func__, __FILE__, __LINE__);
 }
 
-void (*godot_rb_cleanup_functions[GDEXTENSION_MAX_INITIALIZATION_LEVEL])(void) = {
+static void (* const godot_rb_cleanup_functions[GDEXTENSION_MAX_INITIALIZATION_LEVEL])(void) = {
   [GDEXTENSION_INITIALIZATION_CORE] = godot_rb_cleanup_core
 };
 void godot_rb_cleanup(__attribute__((unused)) void* userdata, GDExtensionInitializationLevel p_level) {
   void (*func)(void) = godot_rb_cleanup_functions[p_level];
   if(func) {
     printf("cleaning up Godot.rb init level %u...\n", p_level);
-    func();
-    godot_rb_init_levels[p_level] = false;
-    printf("Godot.rb init level %u cleaned up.\n", p_level);
+    if(godot_rb_init_levels[p_level]) {
+      func();
+      godot_rb_init_levels[p_level] = false;
+      printf("Godot.rb init level %u cleaned up.\n", p_level);
+    } else
+      godot_rb_warn("Godot.rb hasn't set this init level up.", __func__, __FILE__, __LINE__);
   }
 }

src/setup.c

@@ -1,22 +1,21 @@
 #include "setup.h"
 
 static char* arg0 = "main";
-bool godot_rb_setup_core(void) {
+static bool godot_rb_setup_core(void) {
   // On Windows, the argc/v pointers are rather return vars as their original contents are discarded.
   // https://github.com/ruby/ruby/blob/v3_2_2/win32/win32.c#L923-L926
   int argc = 1;
   char** argv = &arg0;
   ruby_sysinit(&argc, &argv);
-  int err = ruby_setup();
-  if(err) {
+  if(ruby_setup()) {
     godot_rb_error("Ruby ran into a problem while starting.", __func__, __FILE__, __LINE__);
     return false;
   }
   ruby_script("godot_rb.c");
   return true;
 }
 
-bool (*godot_rb_setup_functions[GDEXTENSION_MAX_INITIALIZATION_LEVEL])(void) = {
+static bool (* const godot_rb_setup_functions[GDEXTENSION_MAX_INITIALIZATION_LEVEL])(void) = {
   [GDEXTENSION_INITIALIZATION_CORE] = godot_rb_setup_core
 };
 // Ruby keeps a copy of the argc/v pointers’ contents, though it seems to only use `argv[0]` occasionally.