fix: no_of_last_blocks if greater than blockchain height

https://github.com/moneroexamples/onion-monero-blockchain-explorer/
issues/141

src/page.h

@@ -582,12 +582,12 @@ index2(uint64_t page_no = 0, bool refresh_page = false)
 
     uint64_t local_copy_server_timestamp = server_timestamp;
 
-    // number of last blocks to show
-    uint64_t no_of_last_blocks {no_blocks_on_index + 1};
-
     // get the current blockchain height. Just to check
     uint64_t height = core_storage->get_current_blockchain_height();
 
+    // number of last blocks to show
+    uint64_t no_of_last_blocks = std::min(no_blocks_on_index + 1, height);
+
     // initalise page tempate map with basic info about blockchain
     mstch::map context {
             {"testnet"                  , testnet},