Fix max by for getBlockCount (#1951)

* Fix max by for getBlockCount

* Add helper func to package

chain/src/main/scala/org/bitcoins/chain/models/BlockHeaderDAO.scala

@@ -260,7 +260,9 @@ case class BlockHeaderDAO()(implicit
 
   /** Returns the block height of the block with the most work from our database */
   def bestHeight: Future[Int] = {
-    chainTips.map(_.maxBy(_.chainWork).height)
+    chainTips.map { tips =>
+      tips.maxByOption(_.chainWork).map(_.height).getOrElse(0)
+    }
   }
 
   private val maxWorkQuery: profile.ProfileAction[

core/src/main/scala/org/bitcoins/core/package.scala

@@ -8,9 +8,29 @@ import org.bitcoins.core.wallet.fee.SatoshisPerKiloByte
 import scodec.bits._
 
 import scala.annotation.tailrec
+import scala.math.Ordering
 
 package object core {
 
+  implicit class seqUtil[T](private val seq: Seq[T]) extends AnyVal {
+
+    def maxByOption[B](f: T => B)(implicit cmp: Ordering[B]): Option[T] = {
+      if (seq.isEmpty) {
+        None
+      } else {
+        Some(seq.maxBy(f))
+      }
+    }
+
+    def minByOption[B](f: T => B)(implicit cmp: Ordering[B]): Option[T] = {
+      if (seq.isEmpty) {
+        None
+      } else {
+        Some(seq.minBy(f))
+      }
+    }
+  }
+
   implicit val satoshisPerKiloByteOrdering: Ordering[SatoshisPerKiloByte] =
     new Ordering[SatoshisPerKiloByte] {