fix dumb type error and some linting things

packages/gatsby/gatsby-browser.js

@@ -19,7 +19,7 @@ exports.onClientEntry = function(_, pluginParams) {
 
     const integrations = [...(pluginParams.integrations || [])];
 
-    if (hasTracingEnabled()) {
+    if (hasTracingEnabled(pluginParams)) {
       if (BrowserTracingIntegration) {
         integrations.push(new BrowserTracingIntegration());
       } else if (TracingIntegration) {

packages/tracing/src/hubextensions.ts

@@ -1,9 +1,9 @@
 import { getMainCarrier, Hub } from '@sentry/hub';
 import { SampleContext, TransactionContext } from '@sentry/types';
+import { hasTracingEnabled, logger } from '@sentry/utils';
 
 import { IdleTransaction } from './idletransaction';
 import { Transaction } from './transaction';
-import { hasTracingEnabled, logger } from '@sentry/utils';
 
 /** Returns all trace headers that are currently on the top scope. */
 function traceHeaders(this: Hub): { [key: string]: string } {
@@ -32,17 +32,17 @@ function traceHeaders(this: Hub): { [key: string]: string } {
  * Mutates the given Transaction object and then returns the mutated object.
  */
 function sample<T extends Transaction>(hub: Hub, transaction: T): T {
+  const client = hub.getClient();
+  const options = (client && client.getOptions()) || {};
+
   // nothing to do if tracing is disabled
-  if (!hasTracingEnabled(hub)) {
+  if (!hasTracingEnabled(options)) {
     transaction.sampled = false;
     return transaction;
   }
 
   logger.log('Tracing enabled');
 
-  const client = hub.getClient();
-  const options = (client && client.getOptions()) || {};
-
   // we have to test for a pre-existsing sampling decision, in case this transaction is a child transaction and has
   // inherited its parent's decision
   if (transaction.sampled === undefined) {

packages/types/src/options.ts

@@ -2,8 +2,8 @@ import { Breadcrumb, BreadcrumbHint } from './breadcrumb';
 import { Event, EventHint } from './event';
 import { Integration } from './integration';
 import { LogLevel } from './loglevel';
-import { Transport, TransportClass, TransportOptions } from './transport';
 import { SampleContext } from './transaction';
+import { Transport, TransportClass, TransportOptions } from './transport';
 
 /** Base configuration options for every SDK. */
 export interface Options {
@@ -82,16 +82,13 @@ export interface Options {
   /**
    * Sample rate to determine trace sampling.
    *
-   * 0.0 = 0% chance of instrumenting
-   * 1.0 = 100% chance of instrumenting
+   * 0.0 = 0% chance of a given trace being sent (send no traces)
+   * 1.0 = 100% chance of a given trace being sent (send all traces)
    *
-   * Default: 0.0
+   * Can be omitted without disabling tracing if `tracesSampler` is defined. If neither is defined, tracing is disabled.
    */
   tracesSampleRate?: number;
 
-  /** Function to compute tracing sample rate dynamically and filter unwanted traces */
-  tracesSampler?(traceContext: SampleContext): number | null;
-
   /** Attaches stacktraces to pure capture message / log integrations */
   attachStacktrace?: boolean;
 
@@ -148,4 +145,13 @@ export interface Options {
    * @returns The breadcrumb that will be added | null.
    */
   beforeBreadcrumb?(breadcrumb: Breadcrumb, hint?: BreadcrumbHint): Breadcrumb | null;
+
+  /**
+   * Function to compute tracing sample rate dynamically and filter unwanted traces.
+   *
+   * Can be defined in place of `tracesSampleRate`. If neither is defined, tracing is disabled.
+   *
+   * @returns A sample rate or `null` to drop the trace.
+   */
+  tracesSampler?(traceContext: SampleContext): number | null;
 }

packages/utils/src/misc.ts

@@ -1,5 +1,5 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import { Event, Hub, Integration, StackFrame, WrappedFunction } from '@sentry/types';
+import { Event, Integration, Options, StackFrame, WrappedFunction } from '@sentry/types';
 
 import { isString } from './is';
 import { snipLine } from './string';
@@ -516,9 +516,6 @@ export function addContextToFrame(lines: string[], frame: StackFrame, linesOfCon
  *
  * Tracing is enabled when at least one of `tracesSampleRate` and `tracesSampler` is defined in the SDK config.
  */
-export function hasTracingEnabled(hub: Hub): boolean {
-  const client = hub.getClient();
-  const options = (client && client.getOptions()) || {};
-
+export function hasTracingEnabled(options: Options): boolean {
   return !!options.tracesSampleRate || !!options.tracesSampler;
 }