Fix crash in memory viewer launcher (#17152)

rpcs3/rpcs3qt/instruction_editor_dialog.cpp

@@ -22,7 +22,7 @@ instruction_editor_dialog::instruction_editor_dialog(QWidget *parent, u32 _pc, C
 	: QDialog(parent)
 	, m_pc(_pc)
 	, m_disasm(_disasm->copy_type_erased())
-	, m_get_cpu(std::move(func))
+	, m_get_cpu(func ? std::move(func) : std::function<cpu_thread*()>(FN(nullptr)))
 {
 	setWindowTitle(tr("Edit instruction"));
 	setAttribute(Qt::WA_DeleteOnClose);

rpcs3/rpcs3qt/memory_viewer_panel.cpp

@@ -35,7 +35,7 @@ constexpr auto qstr = QString::fromStdString;
 memory_viewer_panel::memory_viewer_panel(QWidget* parent, std::shared_ptr<CPUDisAsm> disasm, u32 addr, std::function<cpu_thread*()> func)
 	: QDialog(parent)
 	, m_addr(addr)
-	, m_get_cpu(std::move(func))
+	, m_get_cpu(func ? std::move(func) : std::function<cpu_thread*()>(FN(nullptr)))
 	, m_type([&]()
 	{
 		const auto cpu = m_get_cpu();

rpcs3/rpcs3qt/register_editor_dialog.cpp

@@ -62,7 +62,7 @@ enum registers : int
 register_editor_dialog::register_editor_dialog(QWidget *parent, CPUDisAsm* _disasm, std::function<cpu_thread*()> func)
 	: QDialog(parent)
 	, m_disasm(_disasm)
-	, m_get_cpu(std::move(func))
+	, m_get_cpu(func ? std::move(func) : std::function<cpu_thread*()>(FN(nullptr)))
 {
 	setWindowTitle(tr("Edit registers"));
 	setAttribute(Qt::WA_DeleteOnClose);