fix(extensions): handle individual extension update check failures

checkForAllExtensionUpdates() used Promise.all without per-promise
catch handlers. A single extension's update check failure would reject
the entire batch, leaving remaining extensions stuck in
CHECKING_FOR_UPDATES state. Now catches per-extension and reports ERROR.

packages/core/src/extension/extensionManager.ts

@@ -1232,9 +1232,9 @@ export class ExtensionManager {
       }
       callback(extension.name, ExtensionUpdateState.CHECKING_FOR_UPDATES);
       promises.push(
-        checkForExtensionUpdate(extension, this).then((state) =>
+        checkForExtensionUpdate(extension, this)
-          callback(extension.name, state),
+          .then((state) => callback(extension.name, state))
-        ),
+          .catch(() => callback(extension.name, ExtensionUpdateState.ERROR)),
       );
     }
     await Promise.all(promises);