[K/N] Replaced usage of minBy/maxBy in samples and benchmarks

kotlin-native/performance/ring/src/main/kotlin/org/jetbrains/ring/GraphSolverBenchmark.kt

@@ -33,7 +33,7 @@ class Greedy(private val graph: Graph) {
         val nodes = node.neighbors
                 .filter { it.value != 0 && !visitedNodes.contains(it.key) }
         val clostest = nodes
-                .minBy { it.value }!!
+                .minByOrNull { it.value }!!
         return ClosestNode(clostest.key, clostest.value)
     }
 

kotlin-native/samples/torch/src/torchMain/kotlin/ClassifierDemo.kt

@@ -17,7 +17,7 @@ fun Float.toRoundedString(digits: Int = 0): String {
 
 fun Float.toPercentageString(roundToDigits: Int = 1) = (this * 100).toRoundedString(roundToDigits)
 
-fun List<Float>.maxIndex() = withIndex().maxBy { it.value }!!.index
+fun List<Float>.maxIndex() = withIndex().maxByOrNull { it.value }!!.index
 
 fun accuracy(predictionBatch: FloatMatrix, labelBatch: FloatMatrix): Float {
     val resultIndexes = predictionBatch.toList().map { it.maxIndex() }