Evaluate nil check necessity

Before adding nil checks, evaluate whether they are actually necessary or if they represent false positives from static analysis tools. Consider Go’s built-in nil safety patterns and semantics.

Key principles:

1. Add explicit nil validation for public API parameters that could reasonably be nil, especially when the function would panic or behave unexpectedly
2. Question nil checks flagged by static analysis tools - tools like nilaway can produce false positives where nil states are impossible given the code flow
3. Leverage Go’s nil-safe operations - operations like len(data) return 0 for nil slices/maps, making explicit nil checks often redundant
4. Distinguish between nil and zero values - understand that []string{} (empty slice) and []string(nil) (nil slice) have different semantics, though both have length 0

Example of necessary nil check:

// NewWithClient creates a client from an existing fasthttp.Client
func NewWithClient(c *fasthttp.Client) *Client {
    if c == nil {
        panic("client cannot be nil")
    }
    return &Client{client: c}
}

Example of unnecessary nil check:

func parseToStruct(data map[string][]string) error {
    // Unnecessary: len(nil) == 0 in Go
    if data == nil {
        return nil
    }
    // Better: direct length check handles nil case
    if len(data) == 0 {
        return nil
    }
}

When in doubt, consider: “Can this value actually be nil given the calling context?” and “Does Go already handle this nil case safely?”