KT-10139:

Non-exhaustive 'when' without 'else' used in expression is an error
regardless of expected type: it can't be an expression, even of type Unit.

compiler/testData/codegen/box/when/noElseAssigned.kt

@@ -1,9 +0,0 @@
-fun box(): String {
-    var r = "Fail 0"
-    val x = 1
-    val y: Unit = when (x) {
-        1 -> { r = "OK" }
-        2 -> { r = "Fail 1" }
-    }
-    return r
-}

compiler/testData/codegen/box/when/noElseAssignedNoMatch.kt

@@ -1,9 +0,0 @@
-fun box(): String {
-    var r = "OK"
-    val x = 3
-    val y: Unit = when (x) {
-        1 -> { r = "Fail 0" }
-        2 -> { r = "Fail 1" }
-    }
-    return r
-}

compiler/testData/codegen/box/when/noElseInRetunedExpression.kt

@@ -1,11 +0,0 @@
-var r = "Fail 0"
-
-fun foo(x: Int) {
-    return when (x) {
-        1 -> { r = "OK" }
-    }
-}
-fun box(): String {
-    foo(1)
-    return r
-}

compiler/testData/codegen/box/when/noElseInRetunedExpressionNoMatch.kt

@@ -1,11 +0,0 @@
-var r = "OK"
-
-fun foo(x: Int) {
-    return when (x) {
-        1 -> { r = "Fail" }
-    }
-}
-fun box(): String {
-    foo(0)
-    return r
-}