JVM_IR: Add null-checks in SAM wrapper constructors (KT-50108)

compiler/testData/codegen/box/sam/kt50108.kt

@@ -0,0 +1,32 @@
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND: JVM
+
+fun interface IFoo {
+    fun foo(): String
+}
+
+abstract class Base {
+    abstract val fn: () -> String
+
+    init {
+        // This should throw a NPE, since the constructor of the IFoo
+        // SAM wrapper expects a non-nullable function type.
+        //
+        // In the JVM backend this expression evaluates to `null` instead,
+        // which isn't a valid result according to the type system.
+        IFoo(fn)
+    }
+}
+
+class Derived : Base() {
+    override val fn: () -> String = { "OK" }
+}
+
+fun box(): String {
+    try {
+        Derived()
+    } catch (e: java.lang.NullPointerException) {
+        return "OK"
+    }
+    return "Fail"
+}

compiler/testData/codegen/box/sam/kt50108_java.kt

@@ -0,0 +1,23 @@
+// TARGET_BACKEND: JVM
+// FILE: test.kt
+fun interface IFoo {
+    fun foo(s: String)
+}
+
+val foo = IFoo {}
+
+fun box(): String {
+    try {
+        J.callWithNull(foo)
+        return "J.callWithNull(foo) should throw NPE"
+    } catch (e: NullPointerException) {
+        return "OK"
+    }
+}
+
+// FILE: J.java
+public class J {
+    public static void callWithNull(IFoo iFoo) {
+        iFoo.foo(null);
+    }
+}