When generating the error message, don't overrun args.nodes .

frog/minfrog

 #!/usr/bin/env node
 //  ********** Library dart:core **************
 //  ********** Natives dart:core **************
 /**
  * Generates a dynamic call stub for a function.
  * Our goal is to create a stub method like this on-the-fly:
  *   function($0, $1, capture) { return this($0, $1, true, capture); }
  *
  * This stub then replaces the dynamic one on Function, with one that is
  * specialized for that particular function, taking into account its default
@@ skipping 5577 matching lines @@
       var arg = args.getValue(this.parameters.$index(i).get$name());
       if (arg == null) {
         arg = this.parameters.$index(i).get$value();
       }
       else {
         arg = arg.convertTo$4(context, this.parameters.$index(i).get$type(), node, isDynamic);
         namedArgsUsed++;
       }
       if (arg == null || !this.parameters.$index(i).get$isOptional()) {
         var msg = MethodMember._argCountMsg(Math.min(i, args.get$length()), i + 1, true);
-        return this._argError(context, node, target, args, msg, args.nodes.$index(i).get$span());
+        return this._argError(context, node, target, args, msg, (i >= args.nodes.get$length()) ? node.span : args.nodes.$index(i).get$span());
       }
       else {
         argsCode.add$1(this.isConst && arg.get$isConst() ? arg.get$canonicalCode() : arg.get$code());
       }
     }
     Arguments.removeTrailingNulls(argsCode);
   }
   if (namedArgsUsed < args.get$nameCount()) {
     var seen = new HashSetImplementation();
     for (var i = bareCount;
@@ skipping 7829 matching lines @@
 }
 var const$0 = new EnvMap()/*const EnvMap()*/;
 var const$127 = new IllegalAccessException()/*const IllegalAccessException()*/;
 var const$128 = ImmutableList.ImmutableList$from$factory([])/*const []*/;
 var const$2 = new EmptyQueueException()/*const EmptyQueueException()*/;
 var const$3 = new _DeletedKeySentinel()/*const _DeletedKeySentinel()*/;
 var const$8 = new NoMoreElementsException()/*const NoMoreElementsException()*/;
 var $globals = {};
 $static_init();
 main();