Make view result optional

In case it's not managed by a comm

Author: lionel-

positron/comms/variables-backend-openrpc.json

@@ -186,7 +186,8 @@
 				"schema": {
 					"description": "The ID of the viewer that was opened.",
 					"type": "string"
-				}
+				},
+				"required": false
 			}
 		}
 	],

src/vs/workbench/contrib/positronVariables/browser/components/variableItem.tsx

@@ -138,10 +138,10 @@ export const VariableItem = (props: VariableItemProps) => {
 			}
 
 			// If a binding was returned, save the binding between the viewer and the
-			// variable item. Note that we intentionally treat `""` as falsy here so
-			// that backends can return an empty ID if no comm was open. This happens
-			// with Ark when the user views a function object: a virtual document is
-			// opened in an editor but is not managed by a comm.
+			// variable item. Note that it's valid for backends to not return any ID
+			// if no comm was open. This happens with Ark when the user views a
+			// function object: a virtual document is opened in an editor but is not
+			// managed by a comm.
 			if (viewerId) {
 				explorerService.setInstanceForVar(viewerId, item.id);
 			}

src/vs/workbench/services/languageRuntime/common/positronVariablesComm.ts

@@ -415,7 +415,7 @@ export class PositronVariablesComm extends PositronBaseComm {
 	 *
 	 * @returns The ID of the viewer that was opened.
 	 */
-	view(path: Array<string>): Promise<string> {
+	view(path: Array<string>): Promise<string | undefined> {
 		return super.performRpc('view', ['path'], [path]);
 	}