Process request for searching class with empty qualified name without errors

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/CliLightClassGenerationSupport.kt

@@ -166,6 +166,8 @@ public class CliLightClassGenerationSupport(project: Project) : LightClassGenera
     }
 
     override fun findFilesForFacade(facadeFqName: FqName, scope: GlobalSearchScope): Collection<JetFile> {
+        if (facadeFqName.isRoot) return emptyList()
+
         return PackagePartClassUtils.getFilesWithCallables(findFilesForPackage(facadeFqName.parent(), scope)).filter {
             JvmFileClassUtil.getFileClassInfoNoResolve(it).facadeClassFqName == facadeFqName
         }

compiler/light-classes/src/org/jetbrains/kotlin/asJava/JavaElementFinder.java

@@ -146,6 +146,8 @@ public class JavaElementFinder extends PsiElementFinder implements KotlinFinderM
     }
 
     private void findInterfaceDefaultImpls(FqName qualifiedName, GlobalSearchScope scope, List<PsiClass> answer) {
+        if (qualifiedName.isRoot()) return;
+
         if (!qualifiedName.shortName().asString().equals(JvmAbi.DEFAULT_IMPLS_CLASS_NAME)) return;
 
         for (JetClassOrObject classOrObject : lightClassGenerationSupport.findClassOrObjectDeclarations(qualifiedName.parent(), scope)) {

compiler/tests/org/jetbrains/kotlin/asJava/JavaElementFinderTest.java

@@ -47,6 +47,10 @@ public class JavaElementFinderTest extends KotlinAsJavaTestBase {
         // TODO: assertClass("Direction.WEST.Some");
     }
 
+    public void testEmptyQualifiedName() {
+        assertNoClass("");
+    }
+
     private void assertClass(String qualifiedName) {
         PsiClass psiClass = finder.findClass(qualifiedName, GlobalSearchScope.allScope(getProject()));
         assertNotNull(String.format("Class with fqn='%s' wasn't found.", qualifiedName), psiClass);