KT-12254 Prevent JsEmptyExpression from getting into initializer JS when compiling code like val x = throw Exception()

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/InitializerTest.java

@@ -34,4 +34,8 @@ public class InitializerTest extends SingleFileTranslationTest {
     public void testClassInitializer() throws Exception {
         checkFooBoxIsOk();
     }
+
+    public void testDeclarationInitializedWithThrow() throws Exception {
+        checkFooBoxIsOk();
+    }
 }

js/js.translator/src/org/jetbrains/kotlin/js/translate/initializer/InitializerVisitor.java

@@ -21,6 +21,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.kotlin.js.translate.context.TranslationContext;
 import org.jetbrains.kotlin.js.translate.general.Translation;
 import org.jetbrains.kotlin.js.translate.general.TranslatorVisitor;
+import org.jetbrains.kotlin.js.translate.utils.JsAstUtils;
 import org.jetbrains.kotlin.psi.*;
 
 import java.util.List;
@@ -46,8 +47,11 @@ public final class InitializerVisitor extends TranslatorVisitor<Void> {
     public final Void visitProperty(@NotNull KtProperty property, @NotNull TranslationContext context) {
         KtExpression initializer = property.getInitializer();
         if (initializer != null) {
-            result.add(generateInitializerForProperty(context, getPropertyDescriptor(context.bindingContext(), property),
+            JsStatement statement = generateInitializerForProperty(context, getPropertyDescriptor(context.bindingContext(), property),
-                                                      Translation.translateAsExpression(initializer, context)));
+                                                                   Translation.translateAsExpression(initializer, context));
+            if (!JsAstUtils.isEmptyStatement(statement)) {
+                result.add(statement);
+            }
         }
 
         JsStatement delegate = generateInitializerForDelegate(context, property);

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/TranslationUtils.java

@@ -175,7 +175,7 @@ public final class TranslationUtils {
             @NotNull PropertyDescriptor descriptor,
             @NotNull JsExpression assignTo) {
         JsNameRef backingFieldReference = backingFieldReference(context, descriptor);
-        return assignment(backingFieldReference, assignTo);
+        return !JsAstUtils.isEmptyExpression(assignTo) ? assignment(backingFieldReference, assignTo) : assignTo;
     }
 
     @Nullable

js/js.translator/testData/initialize/cases/declarationInitializedWithThrow.kt

@@ -0,0 +1,15 @@
+// See KT-12254
+package foo
+
+object A {
+    var x: Int = throw RuntimeException("catch me")
+}
+
+fun box(): String {
+    try {
+        return "fail: ${A.x.toString()}"
+    }
+    catch (e: RuntimeException) {
+        return if (e.message == "catch me") "OK" else "fail: ${e.message}"
+    }
+}