JS: throw exception when accessing uninitialized lateinit property (KT-14964)

js/js.translator/testData/box/initialize/uninitializedLateinit.kt

@@ -0,0 +1,62 @@
+// EXPECTED_REACHABLE_NODES: 1059
+// MODULE: lib
+// FILE: lib.kt
+open class A {
+    private lateinit var a: Any
+    open lateinit var c: Any
+
+    fun useA() = a
+    fun useC() = c
+
+    companion object {
+        lateinit var b: Any
+
+        fun useB() = b
+    }
+}
+
+object O {
+    lateinit var o: Any
+
+    fun useO() = o
+}
+
+fun <T> checkException(propertyName: String, f: () -> T) {
+    try {
+        f()
+    }
+    catch (e: kotlin.UninitializedPropertyAccessException) {
+        assertEquals(e.message, "lateinit property ${propertyName} has not been initialized")
+    }
+}
+
+fun runChecks() {
+    checkException("a") { A().useA() }
+    checkException("b") { A.b }
+    checkException("b") { A.useB() }
+    checkException("o") { O.o }
+    checkException("o") { O.useO() }
+}
+
+// MODULE: main(lib)
+// FILE: main.kt
+
+class C: A() {
+    override lateinit var c: Any
+}
+
+fun box(): String {
+    runChecks()
+
+    checkException("a") { A().useA() }
+    checkException("b") { A.b }
+    checkException("b") { A.useB() }
+    checkException("o") { O.o }
+    checkException("o") { O.useO() }
+
+    checkException("a") { C().useA() }
+    checkException("c") { C().c }
+    checkException("c") { C().useC() }
+
+    return "OK"
+}