fix context::run_script() with syntax error

Return empty result handle for a script with syntax error,
do not catch JavaScript exception.

Added a  test case.

See issue #80

Author: pmed

test/test_context.cpp

@@ -17,8 +17,14 @@ void test_context()
 		v8pp::context context;
 
 		v8::HandleScope scope(context.isolate());
-		int const r = context.run_script("42")->Int32Value(context.isolate()->GetCurrentContext()).FromJust();
+		v8::Local<v8::Value> result = context.run_script("42");
+		int const r = result->Int32Value(context.isolate()->GetCurrentContext()).FromJust();
 		check_eq("run_script", r, 42);
+
+		v8::TryCatch try_catch(context.isolate());
+		result = context.run_script("syntax error");
+		check("script with syntax error", result.IsEmpty());
+		check(" has caught", try_catch.HasCaught());
 	}
 
 	{

v8pp/context.cpp

@@ -259,8 +259,9 @@ v8::Local<v8::Value> context::run_script(std::string const& source,
 	v8::Local<v8::Context> context = isolate_->GetCurrentContext();
 
 	v8::ScriptOrigin origin(to_v8(isolate_, filename));
-	v8::Local<v8::Script> script = v8::Script::Compile(context,
-		to_v8(isolate_, source), &origin).ToLocalChecked();
+	v8::Local<v8::Script> script;
+	bool const is_valid = v8::Script::Compile(context,
+		to_v8(isolate_, source), &origin).ToLocal(&script);
 
 	v8::Local<v8::Value> result;
 	if (!script.IsEmpty())