ViewPolicy LiteParsedExtensionExpanded::getViewPolicy():
    if featureFlagExtensionStageOnView is not enabled:
        // TODO decide what should happen with $rerank

        if stageName is not $vectorSearch:
            uassert that extension stages are not yet supported on views
        else:
            // uassert to kick-back to retry runAggregate() with $vectorSearch using 
            // legacy implementation 
            uassert(FeatureFlagRetryInfo(featureFlagVectorSearchExtension, false));

    // continue with extensions-on-views logic in development