null check

plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java

diff --git a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
index 9b50a69..953f126 100644
--- a/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
+++ b/plugins/org.eclipse.dltk.javascript.core/src/org/eclipse/dltk/internal/javascript/ti/TypeInferencerVisitor.java
@@ -596,8 +596,10 @@
 					&& RTypes.OBJECT.getDeclaration().equals(
 							method.getDeclaringType()) && arguments.length > 0) {
 				AnonymousValue value = new AnonymousValue();
-				value.getValue().addValue(
-						((IValueProvider) arguments[0]).getValue());
+				IValue argumentValue = ((IValueProvider) arguments[0])
+						.getValue();
+				if (argumentValue != null)
+					value.getValue().addValue(argumentValue);
 				if (arguments.length == 2) {
 					JSTypeSet types = arguments[1].getTypes();
 					for (IRType type : types) {