Buggy code:
//*  * Copyright 2007 The Closure Compiler Authors.  *  * Licensed under the Apache License, Version 2.0 (the "License");  * you may not use this file except in compliance with the License.  * You may obtain a copy of the License at  *  *     http: *  * Unless required by applicable law or agreed to in writing, software  * distributed under the License is distributed on an "AS IS" BASIS,  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  * See the License for the specific language governing permissions and  * limitations under the License.  *//  package com.google.javascript.jscomp;  import com.google.common.base.Preconditions; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Lists; import com.google.javascript.rhino.Node; import com.google.javascript.rhino.Token; import com.google.javascript.rhino.jstype.FunctionType; import com.google.javascript.rhino.jstype.JSTypeNative; import com.google.javascript.rhino.jstype.ObjectType;  import java.util.Collection; import java.util.List; import java.util.Set;   //**  * This describes the Closure-specific JavaScript coding conventions.  *  *// public class ClosureCodingConvention extends DefaultCodingConvention {    private static final long serialVersionUID = 1L;    static final DiagnosticType OBJECTLIT_EXPECTED = DiagnosticType.warning(       "JSC_REFLECT_OBJECTLIT_EXPECTED",       "Object literal expected as second argument");    //**    * Closure's goog.inherits adds a {@code superClass_} property to the    * subclass, and a {@code constructor} property.    *//   @Override   public void applySubclassRelationship(FunctionType parentCtor,       FunctionType childCtor, SubclassType type) {     if (type == SubclassType.INHERITS) {       childCtor.defineDeclaredProperty("superClass_",           parentCtor.getPrototype(), parentCtor.getSource());       childCtor.getPrototype().defineDeclaredProperty("constructor",           childCtor, parentCtor.getSource());     }   }    //**    * {@inheritDoc}    *    * <p>Understands several different inheritance patterns that occur in    * Google code (various uses of {@code inherits} and {@code mixin}).    *//   @Override   public SubclassRelationship getClassesDefinedByCall(Node callNode) {     Node callName = callNode.getFirstChild();     SubclassType type = typeofClassDefiningName(callName);     if (type != null) {       Node subclass = null;       Node superclass = callNode.getLastChild();                                                  boolean isDeprecatedCall = callNode.getChildCount() == 2 &&           callName.getType() == Token.GETPROP;       if (isDeprecatedCall) {                 subclass = callName.getFirstChild();       } else if (callNode.getChildCount() == 3) {                 subclass = callName.getNext();       } else {         return null;       }        if (type == SubclassType.MIXIN) {                         if (!endsWithPrototype(superclass)) {           return null;         }         if (!isDeprecatedCall) {           if (!endsWithPrototype(subclass)) {             return null;           }                     subclass = subclass.getFirstChild();         }         superclass = superclass.getFirstChild();       }                                if (subclass != null &&           subclass.isUnscopedQualifiedName() &&           superclass.isUnscopedQualifiedName()) {         return new SubclassRelationship(type, subclass, superclass);       }     }      return null;   }    //**    * Determines whether the given node is a class-defining name, like    * "inherits" or "mixin."    * @return The type of class-defining name, or null.    *//   private SubclassType typeofClassDefiningName(Node callName) {         String methodName = null;     if (callName.getType() == Token.GETPROP) {       methodName = callName.getLastChild().getString();     } else if (callName.getType() == Token.NAME) {       String name = callName.getString();       int dollarIndex = name.lastIndexOf('$');       if (dollarIndex != -1) {         methodName = name.substring(dollarIndex + 1);       }     }      if (methodName != null) {       if (methodName.equals("inherits")) {         return SubclassType.INHERITS;       } else if (methodName.equals("mixin")) {         return SubclassType.MIXIN;       }     }     return null;   }    @Override   public boolean isSuperClassReference(String propertyName) {     return "superClass_".equals(propertyName);   }    //**    * Given a qualified name node, returns whether "prototype" is at the end.    * For example:    * a.b.c => false    * a.b.c.prototype => true    *//   private boolean endsWithPrototype(Node qualifiedName) {     return qualifiedName.getType() == Token.GETPROP &&         qualifiedName.getLastChild().getString().equals("prototype");   }    //**    * Exctracts X from goog.provide('X'), if the applied Node is goog.    *    * @return The extracted class name, or null.    *//   @Override   public String extractClassNameIfProvide(Node node, Node parent){     return extractClassNameIfGoog(node, parent, "goog.provide");   }    //**    * Exctracts X from goog.require('X'), if the applied Node is goog.    *    * @return The extracted class name, or null.    *//   @Override   public String extractClassNameIfRequire(Node node, Node parent){     return extractClassNameIfGoog(node, parent, "goog.require");   }    private static String extractClassNameIfGoog(Node node, Node parent,       String functionName){     String className = null;     if (NodeUtil.isExprCall(parent)) {       Node callee = node.getFirstChild();       if (callee != null && callee.getType() == Token.GETPROP) {         String qualifiedName = callee.getQualifiedName();         if (functionName.equals(qualifiedName)) {           Node target = callee.getNext();           <START_BUG> if (target != null) { <END_BUG>             className = target.getString();           }         }       }     }     return className;   }    //**    * Use closure's implementation.    * @return closure's function name for exporting properties.    *//   @Override   public String getExportPropertyFunction() {     return "goog.exportProperty";   }    //**    * Use closure's implementation.    * @return closure's function name for exporting symbols.    *//   @Override   public String getExportSymbolFunction() {     return "goog.exportSymbol";   }    @Override   public List<String> identifyTypeDeclarationCall(Node n) {     Node callName = n.getFirstChild();     if ("goog.addDependency".equals(callName.getQualifiedName()) &&         n.getChildCount() >= 3) {       Node typeArray = callName.getNext().getNext();       if (typeArray.getType() == Token.ARRAYLIT) {         List<String> typeNames = Lists.newArrayList();         for (Node name = typeArray.getFirstChild(); name != null;              name = name.getNext()) {           if (name.getType() == Token.STRING) {             typeNames.add(name.getString());           }         }         return typeNames;       }     }     return null;   }    @Override   public String getAbstractMethodName() {     return "goog.abstractMethod";   }    @Override   public String getSingletonGetterClassName(Node callNode) {     Node callArg = callNode.getFirstChild();     String callName = callArg.getQualifiedName();          if (!("goog.addSingletonGetter".equals(callName) ||           "goog$addSingletonGetter".equals(callName)) ||         callNode.getChildCount() != 2) {       return null;     }      return callArg.getNext().getQualifiedName();   }    @Override   public void applySingletonGetter(FunctionType functionType,       FunctionType getterType, ObjectType objectType) {     functionType.defineDeclaredProperty("getInstance", getterType,         functionType.getSource());     functionType.defineDeclaredProperty("instance_", objectType,         functionType.getSource());   }    @Override   public String getGlobalObject() {     return "goog.global";   }    private final Set<String> propertyTestFunctions = ImmutableSet.of(       "goog.isDef", "goog.isNull", "goog.isDefAndNotNull",       "goog.isString", "goog.isNumber", "goog.isBoolean",       "goog.isFunction", "goog.isArray", "goog.isObject");    @Override   public boolean isPropertyTestFunction(Node call) {     Preconditions.checkArgument(call.getType() == Token.CALL);     return propertyTestFunctions.contains(         call.getFirstChild().getQualifiedName());   }    @Override   public ObjectLiteralCast getObjectLiteralCast(NodeTraversal t,       Node callNode) {     Preconditions.checkArgument(callNode.getType() == Token.CALL);     Node callName = callNode.getFirstChild();     if (!"goog.reflect.object".equals(callName.getQualifiedName()) ||         callNode.getChildCount() != 3) {       return null;     }      Node typeNode = callName.getNext();     if (!typeNode.isQualifiedName()) {       return null;     }      Node objectNode = typeNode.getNext();     if (objectNode.getType() != Token.OBJECTLIT) {             t.getCompiler().report(JSError.make(t.getSourceName(), callNode,                                           OBJECTLIT_EXPECTED));       return null;     }      return new ObjectLiteralCast(typeNode.getQualifiedName(),                                  typeNode.getNext());   }    @Override   public boolean isOptionalParameter(Node parameter) {     return false;   }    @Override   public boolean isVarArgsParameter(Node parameter) {     return false;   }    @Override   public boolean isPrivate(String name) {     return false;   }    @Override   public Collection<AssertionFunctionSpec> getAssertionFunctions() {     return ImmutableList.<AssertionFunctionSpec>of(         new AssertionFunctionSpec("goog.asserts.assert"),         new AssertionFunctionSpec("goog.asserts.assertNumber",             JSTypeNative.NUMBER_TYPE),         new AssertionFunctionSpec("goog.asserts.assertString",             JSTypeNative.STRING_TYPE),         new AssertionFunctionSpec("goog.asserts.assertFunction",             JSTypeNative.FUNCTION_INSTANCE_TYPE),         new AssertionFunctionSpec("goog.asserts.assertObject",             JSTypeNative.OBJECT_TYPE),         new AssertionFunctionSpec("goog.asserts.assertArray",             JSTypeNative.ARRAY_TYPE),                         new AssertionFunctionSpec("goog.asserts.assertInstanceof",             JSTypeNative.OBJECT_TYPE)     );   }    @Override   public Bind describeFunctionBind(Node n) {     Bind result = super.describeFunctionBind(n);     if (result != null) {       return result;     }               if (n.getType() != Token.CALL) {       return null;     }      Node callTarget = n.getFirstChild();     String name = callTarget.getQualifiedName();     if (name != null) {       if (name.equals("goog.bind")           || name.equals("goog$bind")) {                 Node fn = callTarget.getNext();         if (fn == null) {           return null;         }         Node thisValue = safeNext(fn);         Node parameters = safeNext(thisValue);         return new Bind(fn, thisValue, parameters);       }        if (name.equals("goog.partial") || name.equals("goog$partial")) {                 Node fn = callTarget.getNext();         if (fn == null) {           return null;         }         Node thisValue = null;         Node parameters = safeNext(fn);         return new Bind(fn, thisValue, parameters);       }     }      return null;   }    private Node safeNext(Node n) {     if (n != null) {       return n.getNext();     }     return null;   } } 

Fix:
if (target != null && target.getType() == Token.STRING) {