Fix Util:ensureFolderExists and XournalMain::migrateSettings

- fs::create_directories may return false even, when one of the paths has been created
 - migrateSettings: tried to migrate a folder which does not even exist.

src/control/XournalMain.cpp

@@ -76,28 +76,28 @@ XournalMain::MigrateResult XournalMain::migrateSettings() {
     fs::path newConfigPath = Util::getConfigFolder();
 
     if (!fs::exists(newConfigPath)) {
-        fs::path oldConfigPath(g_get_home_dir());
-        oldConfigPath /= ".xournalpp";
-
-        if (!fs::exists(oldConfigPath)) {
-            g_message("Migrating configuration from %s to %s", oldConfigPath.string().c_str(),
-                      newConfigPath.string().c_str());
-            auto xdgConfDir = newConfigPath.parent_path();
+        std::array<fs::path, 1> oldPaths = {
+                fs::u8path(g_get_home_dir()) /= ".xournalpp",
+        };
+        for (auto const& oldPath: oldPaths) {
+            if (!fs::is_directory(oldPath)) {
+                continue;
+            }
+            g_message("Migrating configuration from %s to %s", oldPath.c_str(), newConfigPath.c_str());
+            Util::ensureFolderExists(newConfigPath.parent_path());
             try {
-                if (!fs::exists(xdgConfDir)) {
-                    fs::create_directories(xdgConfDir);
-                }
-                fs::copy(oldConfigPath, newConfigPath, fs::copy_options::recursive);
-                const char* msg = "Due to a recent update, Xournal++ has changed where its configuration files are "
-                                  "stored.\nThey have been automatically copied from\n\t{1}\nto\n\t{2}";
+                fs::copy(oldPath, newConfigPath, fs::copy_options::recursive);
+                constexpr auto msg = "Due to a recent update, Xournal++ has changed where it's configuration files are "
+                                     "stored.\nThey have been automatically copied from\n\t{1}\nto\n\t{2}";
                 return {MigrateStatus::Success,
-                        FS(_F(msg) % oldConfigPath.string().c_str() % newConfigPath.string().c_str())};
+                        FS(_F(msg) % oldPath.u8string().c_str() % newConfigPath.u8string().c_str())};
             } catch (fs::filesystem_error const& except) {
-                const char* msg = "Due to a recent update, Xournal++ has changed where its configuration files are "
-                                  "stored.\nHowever, when attempting to copy\n\t{1}\nto\n\t{2}\nmigration failed:\n{3}";
+                constexpr auto msg =
+                        "Due to a recent update, Xournal++ has changed where it's configuration files are "
+                        "stored.\nHowever, when attempting to copy\n\t{1}\nto\n\t{2}\nmigration failed:\n{3}";
                 g_message("Migration failed: %s", except.what());
                 return {MigrateStatus::Failure,
-                        FS(_F(msg) % oldConfigPath.string().c_str() % newConfigPath.string().c_str() % except.what())};
+                        FS(_F(msg) % oldPath.u8string().c_str() % newConfigPath.u8string().c_str() % except.what())};
             }
         }
     }

src/util/PathUtil.cpp

@@ -197,10 +197,12 @@ auto Util::getTmpDirSubfolder(const fs::path& subfolder) -> fs::path {
 }
 
 auto Util::ensureFolderExists(const fs::path& p) -> fs::path {
-    if (!fs::exists(p) && !fs::create_directories(p)) {
+    try {
+        fs::create_directories(p);
+    } catch (fs::filesystem_error const& fe) {
         Util::execInUiThread([=]() {
-            string msg = FS(_F("Could not create folder: {1}") % p.string());
-            g_warning("%s", msg.c_str());
+            string msg = FS(_F("Could not create folder: {1}\nFailed with error: {2}") % p.string() % fe.what());
+            g_warning("%s %s", msg.c_str(), fe.what());
             XojMsgBox::showErrorToUser(nullptr, msg);
         });
     }