elsi: Fix error when explorer does not exist

src/shell.cpp

@@ -65,9 +65,7 @@ namespace ebridge {
 	std::wstring Shell::GetWorkingDirectory() {
 		auto explorer = GetActiveExplorer();
 		if (!explorer.Exists()) {
-			throw std::runtime_error(
-				"Explorer is not running. "
-				"(Is \"Launch folder windows in a separete process\" enabled?)");
+			throw util::active_explorer_not_found();
 		}
 		return explorer.GetPath();
 	}
@@ -144,7 +142,9 @@ namespace ebridge {
 
 	std::vector<std::wstring> Shell::SelectedItems() {
 		auto explorer = GetActiveExplorer();
-
+		if (!explorer.Exists()) {
+			throw util::active_explorer_not_found();
+		}
 		return explorer.SelectedItems();
 	}
 

src/util.cpp

@@ -4,6 +4,14 @@
 #include <io.h>
 #include "util.h"
 
+util::active_explorer_not_found::active_explorer_not_found() :
+	std::runtime_error(
+		"Explorer is not running. "
+		"(Is \"Launch folder windows in a separete process\" enabled?)"
+	)
+{
+}
+
 std::wstring util::getenv(std::wstring name, std::wstring default_value)
 {
 	wchar_t* buf = nullptr;

src/util.h

@@ -3,6 +3,11 @@
 
 namespace util {
 	class silent_error {};
+	class active_explorer_not_found : public std::runtime_error
+	{
+	public:
+		active_explorer_not_found();
+	};
 
 	std::wstring getenv(std::wstring name, std::wstring default_value = L"");
 	std::wstring normalize_path_separator(std::wstring path);