fix: string_replace_at check malloc

src/string.c

@@ -67,6 +67,10 @@ char *string_replace_at(const char *src, unsigned int from, unsigned int to,
 
   dst = malloc(src_len - (to - from) + rpl_len + 1);
 
+  if (dst == NULL) {
+    return "";
+  }
+
   strlcpy(dst, src, from + 1);
   strlcpy(dst + from, rpl, rpl_len + 1);
   strlcpy(dst + from + rpl_len, src + to, src_len - to + 1);