Merge pull request #18 from RealAstolfo/realastolfo-time-overflow-fix

added fix for Instant::now() subtraction overflow

src/rpc.rs

@@ -97,7 +97,7 @@ impl Rpc {
             put_queries: HashMap::new(),
             closest_nodes: LruCache::new(NonZeroUsize::new(MAX_CACHED_BUCKETS).unwrap()),
 
-            last_table_refresh: Instant::now() - REFRESH_TABLE_INTERVAL,
+            last_table_refresh: Instant::now().checked_sub(REFRESH_TABLE_INTERVAL).unwrap_or_else(Instant::now),
             last_table_ping: Instant::now(),
         })
     }