fix: null check in str_dup, const in file.c

src/shared/file.c

@@ -189,7 +189,7 @@ bool file_save_to_disk(const char* root_directory, File* file, const Config* con
       if (backup_path) {
         char* backup_dir_path = str_dup(backup_path);
         if (backup_dir_path) {
-          char* bdir = dirname(backup_dir_path);
+          const char* bdir = dirname(backup_dir_path);
           mkdir_r(bdir);
           free(backup_dir_path);
         }

src/shared/utils.c

@@ -58,6 +58,8 @@ char* str_dup(const char* string) {
     return NULL;
   size_t str_len = strlen(string);
   char* new_string = (char*)malloc(str_len + 1);
+  if (new_string == NULL)
+    return NULL;
   memcpy(new_string, string, str_len + 1);
   return new_string;
 }