fix: zero may be a possibility in one of the multiverse

Author: Xstoudi

src/string_bytes.cc

@@ -524,7 +524,7 @@ size_t StringBytes::hex_encode(
     char* dst,
     size_t dlen) {
 
-  CHECK(slen * 2 > slen && "overflow in hex encode");
+  CHECK(slen * 2 >= slen && "overflow in hex encode");
 
   // We know how much we'll write, just make sure that there's space.
   CHECK(dlen >= slen * 2 &&