Specifying an empty string for an argument description crashes schemagen

[wravery]

If you put empty double quotes (or block quotes) in front of a field argument, schemagen crashes when trying to parse the schema:

std::__uniq_ptr_impl<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> >::_M_ptr(const std::__uniq_ptr_impl<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> > * this) (/usr/include/c++/9/bits/unique_ptr.h:154)
std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> >::get(const std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> > * this) (/usr/include/c++/9/bits/unique_ptr.h:361)
std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> >::operator->(const std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> > * this) (/usr/include/c++/9/bits/unique_ptr.h:355)
graphql::schema::Generator::getInputFields(const std::vector<std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> >, std::allocator<std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> > > > & fields) (cppgraphqlgen/src/SchemaGenerator.cpp:1305)
graphql::schema::Generator::getOutputFields(const std::vector<std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> >, std::allocator<std::unique_ptr<graphql::peg::ast_node, std::default_delete<graphql::peg::ast_node> > > > & fields) (cppgraphqlgen/src/SchemaGenerator.cpp:1201)
graphql::schema::Generator::visitObjectTypeExtension(graphql::peg::ast_node const&)::$_7::operator()(graphql::peg::ast_node const&) const(const class {...} * this, const graphql::peg::ast_node & child) (cppgraphqlgen/src/SchemaGenerator.cpp:806)
std::_Function_handler<void (graphql::peg::ast_node const&), graphql::schema::Generator::visitObjectTypeExtension(graphql::peg::ast_node const&)::$_7>::_M_invoke(std::_Any_data const&, graphql::peg::ast_node const&)(const std::_Any_data & __functor, const graphql::peg::ast_node & __args) (/usr/include/c++/9/bits/std_function.h:300)
std::function<void (graphql::peg::ast_node const&)>::operator()(graphql::peg::ast_node const&) const(const std::function<void (const graphql::peg::ast_node &)> * this, const graphql::peg::ast_node & __args) (/usr/include/c++/9/bits/std_function.h:688)
graphql::peg::on_first_child<graphql::peg::fields_definition>(graphql::peg::ast_node const&, std::function<void (graphql::peg::ast_node const&)>&&)(const graphql::peg::ast_node & n, std::function<void (const graphql::peg::ast_node &)> && func) (cppgraphqlgen/include/graphqlservice/GraphQLGrammar.h:44)
graphql::schema::Generator::visitObjectTypeExtension(graphql::schema::Generator * this, const graphql::peg::ast_node & objectTypeExtension) (cppgraphqlgen/src/SchemaGenerator.cpp:803)
graphql::schema::Generator::visitObjectTypeDefinition(graphql::schema::Generator * this, const graphql::peg::ast_node & objectTypeDefinition) (cppgraphqlgen/src/SchemaGenerator.cpp:778)
graphql::schema::Generator::visitDefinition(graphql::schema::Generator * this, const graphql::peg::ast_node & definition) (cppgraphqlgen/src/SchemaGenerator.cpp:715)
graphql::schema::Generator::Generator(graphql::schema::Generator * this, graphql::schema::GeneratorOptions && options) (cppgraphqlgen/src/SchemaGenerator.cpp:291)
main(int argc, char ** argv) (cppgraphqlgen/src/SchemaGenerator.cpp:3585)

The problem is that the children vector of the description node is empty, so de-referencing front() causes a segmentation fault:

else if (child->is_type<peg::description>())
{
	field.description = child->children.front()->unescaped;
}

[wravery]

This is actually a problem everywhere that you can add a description.