wtfutil/wtf · warning

panic(err)

Error message

panic(err)

What it means

NewWithHTTPClient parses the hardcoded defaultAPIURL constant and panics if url.Parse fails. Since the URL is a compile-time constant that is known-valid, this panic is effectively unreachable defensive code — it can only fire if the package constant is modified to an invalid URL (e.g. a fork or patched build).

Source

Thrown at modules/newrelic/client/main.go:36

	// defaultAPIURL is the default base URL for New Relic's latest API.
	defaultAPIURL = "https://api.newrelic.com/v2/"
	// defaultTimeout is the default timeout for the http.Client used.
	defaultTimeout = 5 * time.Second
)

// Client provides a set of methods to interact with the New Relic API.
type Client struct {
	apiKey     string
	httpClient *http.Client
	url        *url.URL
}

// NewWithHTTPClient returns a new Client object for interfacing with the New
// Relic API, allowing for override of the http.Client object.
func NewWithHTTPClient(apiKey string, client *http.Client) *Client {
	u, err := url.Parse(defaultAPIURL)
	if err != nil {
		panic(err)
	}
	return &Client{
		apiKey:     apiKey,
		httpClient: client,
		url:        u,
	}
}

// NewClient returns a new Client object for interfacing with the New Relic API.
func NewClient(apiKey string) *Client {
	return NewWithHTTPClient(apiKey, &http.Client{Timeout: defaultTimeout})
}

View on GitHub (pinned to bb838c1ccb)

Solutions

1. Check whether defaultAPIURL in modules/newrelic/client/main.go was modified and restore/fix the URL value
2. If you intentionally changed it, make the value a syntactically valid absolute URL (scheme + host)
3. Report/verify against upstream if using a fork

Example fix

// before
const defaultAPIURL = "api.newrelic.com" // missing scheme, edited constant
// after
const defaultAPIURL = "https://api.newrelic.com/v2"

// only relevant for forks editing defaultAPIURL
if _, err := url.Parse(defaultAPIURL); err != nil {
    panic(fmt.Sprintf("defaultAPIURL is not a valid URL: %v", err))
}

defer func() {
    if r := recover(); r != nil {
        log.Printf("newrelic client construction panicked: %v", r)
    }
}()
c := newrelic.NewClient(apiKey)

When it happens

Trigger: NewClient → NewWithHTTPClient is called; url.Parse(defaultAPIURL) fails, which for the shipped constant should never happen — realistic only in forks/builds where defaultAPIURL was edited to a malformed string, or in exotic environments where the package was tampered with.

Common situations: Self-patched builds pointing defaultAPIURL at a private New Relic endpoint with a malformed URL value; misapplied patches; vendor-directory edits.

Related errors

• panic(err)
• panic(err)
• panic(err)
• panic(err)
• Key is already mapped to a keyboard command: %s

AI-assisted analysis of wtfutil/wtf@bb838c1ccb (2026-09-03). Data as JSON: /api/errors/893d998c4f413373. Report an issue: GitHub.