fix: copilot comments, add guards for missing configs

src/lez_explorer_ui_backend.cpp

@@ -400,6 +400,14 @@ bool LezExplorerUiBackend::applyConfigJson(QString json) {
 }
 
 bool LezExplorerUiBackend::resetIndexerCache() {
+    // A saved config is required: reset_storage reads the channel from it, and we
+    // restart from it afterwards. Without one there's nothing to reset against, so
+    // don't wipe-then-fail-to-restart.
+    if (readConfigFile().trimmed().isEmpty()) {
+        emit error(QStringLiteral("Save an indexer config before deleting the cache."));
+        return false;
+    }
+
     // reset_storage stops the indexer and deletes its RocksDB store; then we
     // restart from the saved config so it re-indexes the current chain from
     // scratch. The recovery path for a store left stale against a reset chain.

src/qml/pages/SettingsPage.qml

@@ -155,6 +155,13 @@ Item {
     function resetCache() {
         if (!page.backend)
             return;
+        // Nothing to reset to until a config has been saved; don't arm the
+        // destructive confirm — point the user at Save first.
+        if (!page.backend.configText || page.backend.configText.length === 0) {
+            page.confirmingReset = false;
+            page.setStatus("Save an indexer config first, then you can delete the cache.", true);
+            return;
+        }
         if (!page.confirmingReset) {
             page.confirmingReset = true;
             page.setStatus("Click “Confirm delete” to wipe the local index and re-sync from scratch.", true);