WithClientConfig overrides default ClientConfig values with zero values.

While using the Go Typesense client (v3.2.0), I noticed a potential configuration issue related to the functional options pattern and default configuration handling.

In NewClient, a default ClientConfig is initialized with sensible default values:

c := &Client{apiConfig: &ClientConfig{
    RetryInterval:             defaultRetryInterval,
    HealthcheckInterval:       defaultHealthcheckInterval,
    ConnectionTimeout:         defaultConnectionTimeout,
    CircuitBreakerName:        defaultCircuitBreakerName,
    CircuitBreakerMaxRequests: circuit.DefaultGoBreakerMaxRequests,
    CircuitBreakerInterval:    circuit.DefaultGoBreakerInterval,
    CircuitBreakerTimeout:     circuit.DefaultGoBreakerTimeout,
    CircuitBreakerReadyToTrip: circuit.DefaultReadyToTrip,
}}

However, when using the WithClientConfig option:

client := typesense.NewClient(
    typesense.WithClientConfig(&typesense.ClientConfig{
        ServerURL: cfg.ServerURL,
        APIKey:    cfg.APIKey,
    }),
)

The implementation of WithClientConfig assigns all fields from the provided config directly:

func WithClientConfig(config *ClientConfig) ClientOption {
    return func(c *Client) {
        c.apiConfig.ServerURL = config.ServerURL
        c.apiConfig.NearestNode = config.NearestNode
        c.apiConfig.Nodes = config.Nodes
        c.apiConfig.NumRetries = config.NumRetries
        c.apiConfig.RetryInterval = config.RetryInterval
        c.apiConfig.HealthcheckInterval = config.HealthcheckInterval
        c.apiConfig.APIKey = config.APIKey
        c.apiConfig.ConnectionTimeout = config.ConnectionTimeout
        c.apiConfig.CircuitBreakerName = config.CircuitBreakerName
        c.apiConfig.CircuitBreakerMaxRequests = config.CircuitBreakerMaxRequests
        c.apiConfig.CircuitBreakerInterval = config.CircuitBreakerInterval
        c.apiConfig.CircuitBreakerTimeout = config.CircuitBreakerTimeout
        c.apiConfig.CircuitBreakerReadyToTrip = config.CircuitBreakerReadyToTrip
        c.apiConfig.CircuitBreakerOnStateChange = config.CircuitBreakerOnStateChange
    }
}

If only a subset of fields is provided (e.g., only ServerURL and APIKey), the remaining fields are Go zero values and overwrite the defaults set in NewClient.

// implement option pattern
	for _, opt := range opts {
		opt(c)
	}

Question / Clarification

1. Is it the intended behavior that WithClientConfig fully overrides all defaults?
2. Specifically, should NumRetries (and other retry-related fields) have a non-zero default if not explicitly provided?

Start with NewClient and WithClientConfig, focusing on how the option copies ClientConfig fields into the defaults. Determine and document the intended behavior for omitted fields, especially retry and circuit-breaker settings, then add coverage showing the selected behavior for a partial configuration.