Fix NPE in JetPsiUtil (EA-43298)

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java

@@ -362,8 +362,7 @@ public class JetPsiUtil {
             aliasName = referenceExpression != null ? referenceExpression.getReferencedName() : null;
         }
 
-        //noinspection ConstantConditions
-        return !aliasName.isEmpty() ? Name.identifier(aliasName) : null;
+        return aliasName != null && !aliasName.isEmpty() ? Name.identifier(aliasName) : null;
     }
 
     @Nullable

compiler/testData/diagnostics/tests/regressions/ea43298.kt

@@ -0,0 +1,3 @@
+import A.<!SYNTAX!><!>;
+
+class A

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -3319,6 +3319,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 doTest("compiler/testData/diagnostics/tests/regressions/ea40964.kt");
             }
             
+            @TestMetadata("ea43298.kt")
+            public void testEa43298() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/regressions/ea43298.kt");
+            }
+            
             @TestMetadata("ErrorsOnIbjectExpressionsAsParameters.kt")
             public void testErrorsOnIbjectExpressionsAsParameters() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/regressions/ErrorsOnIbjectExpressionsAsParameters.kt");