debugger: add uncaughtException handler to kill child

lib/_debugger.js

@@ -7,6 +7,14 @@ exports.port = 5858;
 
 exports.start = function() {
   var interface = new Interface();
+  process.on('uncaughtException', function (e) {
+    console.error("There was an internal error in Node's debugger. " +
+                  "Please report this bug.");
+    console.error(e.message);
+    console.error(e.stack);
+    if (interface.child) interface.child.kill();
+    process.exit(1);
+  });
 };