Add instructions not to set sideEffects: false in package.json (#13031)

Author: lforst

docs/platforms/javascript/common/troubleshooting/index.mdx

@@ -18,6 +18,14 @@ If you set up the Sentry SDK and it's not sending any data to Sentry:
 - Set `debug: true` in the `Sentry.init()` options and observe your console output when you start your application. The SDK may tell you why it is not sending any data.
 - Check the [Stats](https://sentry.io/orgredirect/organizations/:orgslug/stats/) and [Suscription](https://sentry.io/orgredirect/organizations/:orgslug/settings/billing/overview/) pages in Sentry. You may have ran out of quota.
 
+<PlatformSection supported={["javascript.nextjs"]}>
+  - Check that you didn't set `sideEffects: false` in your `package.json`.
+  Setting `sideEffects` to false in your `package.json` will cause Next.js to
+  tree shake the SDK code too agressively - effectively deleting any
+  `Sentry.init()` calls. Setting `sideEffects: false` is incorrect when you are
+  using the Sentry SDK.
+</PlatformSection>
+
 </Expandable>
 
 <Expandable permalink title="Updating to a new Sentry SDK version">
@@ -448,7 +456,10 @@ shamefully-hoist=true
 ```
 
 <Alert level="warning">
-  **Note**: While `shamefully-hoist=true` usually isn't the ideal solution from a dependency management perspective, it's sometimes necessary for compatibility with certain packages that expect Node.js module resolution behavior similar to npm or yarn.
+  **Note**: While `shamefully-hoist=true` usually isn't the ideal solution from
+  a dependency management perspective, it's sometimes necessary for
+  compatibility with certain packages that expect Node.js module resolution
+  behavior similar to npm or yarn.
 </Alert>
 
   </Expandable>