avoid use-after-free in lambda

[euclio]

Fixes #1449.
Fixes #1439.
Fixes #1402.

The problem here is that if a custom module's JSON fails to parse, then the exception handling code will attempt to log the module name after it's been freed. This may cause name.asString() to throw an exception. This commit fixes the issue by capturing the name by value.

Valgrind output before the change:

valgrind ./build/waybar -c config.json
==94675== Memcheck, a memory error detector
==94675== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==94675== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==94675== Command: ./build/waybar -c config.json
==94675==
==94675== Warning: ignored attempt to set SIGRT32 handler in sigaction();
==94675==          the SIGRT32 signal is used internally by Valgrind
[2022-03-03 19:50:33.668] [info] Using configuration file config.json
[2022-03-03 19:50:33.781] [info] Using CSS file /home/euclio/.config/waybar/style.css
[2022-03-03 19:50:34.337] [warning] module sway/workspaces: Disabling module "sway/workspaces", Socket path is empty
[2022-03-03 19:50:34.400] [warning] module sway/mode: Disabling module "sway/mode", Socket path is empty
[2022-03-03 19:50:34.572] [warning] For a functional tray you must have libappindicator-* installed and export XDG_CURRENT_DESKTOP=Unity
sh: line 1: swaylay: command not found
[2022-03-03 19:50:34.632] [warning] module idle_inhibitor: Disabling module "idle_inhibitor", idle-inhibit not available
[2022-03-03 19:50:34.739] [error] keyboard stopped unexpectedly, is it endless?
[2022-03-03 19:50:35.355] [warning] As using a timezone, some format args may be missing as the date library haven't got a release since 2018.
sh: line 1: /home/euclio/.config/waybar/modules/powermenu.sh: No such file or directory
==94675== Invalid read of size 1
==94675==    at 0x492DDC0: Json::Value::type() const (in /usr/lib/libjsoncpp.so.25)
==94675==    by 0x4934D6E: Json::Value::asString[abi:cxx11]() const (in /usr/lib/libjsoncpp.so.25)
==94675==    by 0x1688AB: waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Gtk::Box*)::{lambda()#1}::operator()() const (bar.cpp:757)
==94675==    by 0x169BCF: sigc::adaptor_functor<waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Gtk::Box*)::{lambda()#1}>::operator()() const (adaptor_trait.h:256)
==94675==    by 0x169A26: sigc::internal::slot_call0<waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Gtk::Box*)::{lambda()#1}, void>::call_it(sigc::internal::slot_rep*) (slot.h:136)
==94675==    by 0x5A6EB39: Glib::DispatchNotifier::pipe_io_handler(Glib::IOCondition) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==94675==    by 0x5A7555B: Glib::IOSource::dispatch(sigc::slot_base*) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==94675==    by 0x5A6E7D6: Glib::Source::dispatch_vfunc(_GSource*, int (*)(void*), void*) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==94675==    by 0x5B7CEE2: g_main_context_dispatch (in /usr/lib/libglib-2.0.so.0.7000.4)
==94675==    by 0x5BD30F8: ??? (in /usr/lib/libglib-2.0.so.0.7000.4)
==94675==    by 0x5B7A454: g_main_context_iteration (in /usr/lib/libglib-2.0.so.0.7000.4)
==94675==    by 0x592D6ED: g_application_run (in /usr/lib/libgio-2.0.so.0.7000.4)
==94675==  Address 0xa0176f8 is 1,416 bytes inside an unallocated block of size 1,744 in arena "client"
==94675==
==94675== Invalid read of size 8
==94675==    at 0x4934D90: Json::Value::asString[abi:cxx11]() const (in /usr/lib/libjsoncpp.so.25)
==94675==    by 0x1688AB: waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Gtk::Box*)::{lambda()#1}::operator()() const (bar.cpp:757)
==94675==    by 0x169BCF: sigc::adaptor_functor<waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Gtk::Box*)::{lambda()#1}>::operator()() const (adaptor_trait.h:256)
==94675==    by 0x169A26: sigc::internal::slot_call0<waybar::Bar::getModules(waybar::Factory const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Gtk::Box*)::{lambda()#1}, void>::call_it(sigc::internal::slot_rep*) (slot.h:136)
==94675==    by 0x5A6EB39: Glib::DispatchNotifier::pipe_io_handler(Glib::IOCondition) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==94675==    by 0x5A7555B: Glib::IOSource::dispatch(sigc::slot_base*) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==94675==    by 0x5A6E7D6: Glib::Source::dispatch_vfunc(_GSource*, int (*)(void*), void*) (in /usr/lib/libglibmm-2.4.so.1.3.0)
==94675==    by 0x5B7CEE2: g_main_context_dispatch (in /usr/lib/libglib-2.0.so.0.7000.4)
==94675==    by 0x5BD30F8: ??? (in /usr/lib/libglib-2.0.so.0.7000.4)
==94675==    by 0x5B7A454: g_main_context_iteration (in /usr/lib/libglib-2.0.so.0.7000.4)
==94675==    by 0x592D6ED: g_application_run (in /usr/lib/libgio-2.0.so.0.7000.4)
==94675==    by 0x17CC49: waybar::Client::main(int, char**) (client.cpp:242)
==94675==  Address 0xa0176f0 is 1,408 bytes inside an unallocated block of size 1,744 in arena "client"
==94675==
[2022-03-03 19:50:37.791] [error] : * Line 1, Column 1
  Syntax error: value, object or array expected.

[2022-03-03 19:50:37.831] [error] : * Line 1, Column 1
  Syntax error: value, object or array expected.

[2022-03-03 19:50:42.682] [info] Bar configured (width: 1920, height: 28) for output: eDP-1

Valgrind reports no issues after this commit.

[superiums]

if name.asString() throws an exception, is it possible to report the line number ? or show line number without module name ?