core: class: validate magic number in class header

core/class.c

@@ -2,6 +2,7 @@
 
 #include "type.h"
 
+#include <assert.h>
 #include <blue/core/class.h>
 #include <stdlib.h>
 #include <string.h>
@@ -18,11 +19,23 @@ void *b_class_get(b_type id)
 
 const char *b_class_get_name(const struct _b_class *c)
 {
+	if (!c) {
+		return NULL;
+	}
+
+	assert(c->c_magic == B_CLASS_MAGIC);
+
 	return c->c_type->r_info->t_name;
 }
 
 void *b_class_get_interface(const struct _b_class *c, const union b_type *id)
 {
+	if (!c) {
+		return NULL;
+	}
+
+	assert(c->c_magic == B_CLASS_MAGIC);
+
 	const struct b_type_registration *type_reg = c->c_type;
 	struct b_type_component *comp
 		= b_type_get_component(&type_reg->r_components, id);