Fixing panic in intelligent, attempted to delete nonexistent key

pkg/storage/drivers/memory/memory_intelligent.go

@@ -134,6 +134,7 @@ func (r *Intelligent) Set(key string, value interface{}) {
 
 // Delete deletes a given key if exists
 func (r *Intelligent) Delete(key string) {
+	if _, ok := r.items[key]; ok {
 		r.currentSize -= uint64(len(r.items[key].([]byte)))
 		delete(r.items, key)
 		delete(r.updatedAt, key)
@@ -141,6 +142,7 @@ func (r *Intelligent) Delete(key string) {
 		if r.OnEvicted != nil {
 			r.OnEvicted(key)
 		}
+	}
 }
 
 func (r *Intelligent) isValid(key string) bool {