Added handling for instance when failure to expand node

Author: Benjin

src/constants/locConstants.ts

@@ -680,6 +680,12 @@ export function enableRichExperiencesPrompt(learnMoreUrl: string) {
 }
 export let enableRichExperiences = l10n.t("Enable Experiences & Reload");
 
+export class ObjectExplorer {
+    public static ErrorLoadingRefreshToTryAgain = l10n.t(
+        "Error loading; refresh to try again",
+    );
+}
+
 export class ConnectionDialog {
     public static connectionDialog = l10n.t("Connection Dialog (Preview)");
     public static azureAccount = l10n.t("Azure Account");

src/objectExplorer/objectExplorerService.ts

@@ -360,7 +360,12 @@ export class ObjectExplorerService {
     private handleExpandSessionNotification(): NotificationHandler<ExpandResponse> {
         const self = this;
         const handler = (result: ExpandResponse) => {
-            if (result && result.nodes) {
+            if (!result) {
+                return undefined;
+            }
+
+            if (result.nodes && !result.errorMessage) {
+                // successfully received children from SQL Tools Service
                 const credentials =
                     self._sessionIdToConnectionCredentialsMap.get(
                         result.sessionId,
@@ -402,6 +407,40 @@ export class ObjectExplorerService {
                         return;
                     }
                 }
+            } else {
+                // failure to expand node; display error
+
+                if (result.errorMessage) {
+                    self._connectionManager.vscodeWrapper.showErrorMessage(
+                        result.errorMessage,
+                    );
+                }
+
+                const expandParams: ExpandParams = {
+                    sessionId: result.sessionId,
+                    nodePath: result.nodePath,
+                };
+                const parentNode = self.getParentFromExpandParams(expandParams);
+
+                const errorNode = new vscode.TreeItem(
+                    LocalizedConstants.ObjectExplorer.ErrorLoadingRefreshToTryAgain,
+                    TreeItemCollapsibleState.None,
+                );
+
+                self._treeNodeToChildrenMap.set(parentNode, [errorNode]);
+
+                for (let key of self._expandParamsToPromiseMap.keys()) {
+                    if (
+                        key.sessionId === expandParams.sessionId &&
+                        key.nodePath === expandParams.nodePath
+                    ) {
+                        let promise = self._expandParamsToPromiseMap.get(key);
+                        promise.resolve([errorNode as TreeNodeInfo]);
+                        self._expandParamsToPromiseMap.delete(key);
+                        self._expandParamsToTreeNodeInfoMap.delete(key);
+                        return;
+                    }
+                }
             }
         };
         return handler;