--- a/nashorn/src/jdk/nashorn/internal/codegen/Lower.java	Tue Jan 08 15:02:36 2013 +0530
+++ b/nashorn/src/jdk/nashorn/internal/codegen/Lower.java	Tue Jan 08 10:52:11 2013 +0100
@@ -1297,7 +1297,10 @@
                     final List<Block> lookupBlocks = findLookupBlocksHelper(getCurrentFunctionNode(), symbol.findFunction());
                     for (final Block lookupBlock : lookupBlocks) {
                         final Symbol refSymbol = lookupBlock.findSymbol(name);
-                        refSymbol.setIsScope();
+                        if (refSymbol != null) { // See NASHORN-837, function declaration in lexical scope: try {} catch (x){ function f() { use(x) } } f()
+                            LOG.finest("Found a ref symbol that must be scope " + refSymbol);
+                            refSymbol.setIsScope();
+                        }
                     }
                 }
             }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/NASHORN-837.js	Tue Jan 08 10:52:11 2013 +0100
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ * 
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ * 
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ * 
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * NASHORN-837 : refSymbol lookup caused nullpointer exception in Lower
+ *
+ * @test
+ * @run
+ */
+
+var failed = false;
+
+try {
+    try {
+	throw new TypeError('error');
+    } catch (iox) {
+	function f() {
+	    print(iox.message);
+	}
+    }
+    f();
+} catch (e) {
+    failed = (e instanceof ReferenceError);
+    //iox not defined should be thrown
+}
+
+if (!failed) {
+    print("Failure! iox did not throw correct exception");
+}
+