move webpack plugin enablement check to function

Author: lobsterkatie

packages/nextjs/src/config/webpack.ts

@@ -134,17 +134,7 @@ export function constructWebpackConfigFunction(
     newConfig.entry = async () => addSentryToEntryProperty(origEntryProperty, buildContext);
 
     // Enable the Sentry plugin (which uploads source maps to Sentry when not in dev) by default
-    const enableWebpackPlugin =
-      // TODO: this is a hack to fix https://github.com/getsentry/sentry-cli/issues/1085, which is caused by
-      // https://github.com/getsentry/sentry-cli/issues/915. Once the latter is addressed, this existence check can come
-      // out. (The check is necessary because currently, `@sentry/cli` uses a post-install script to download an
-      // architecture-specific version of the `sentry-cli` binary. If `yarn install`, `npm install`, or `npm ci` are run
-      // with the `--ignore-scripts` option, this will be blocked and the missing binary will cause an error when users
-      // try to build their apps.)
-      ensureCLIBinaryExists() &&
-      (isServer ? !userSentryOptions.disableServerWebpackPlugin : !userSentryOptions.disableClientWebpackPlugin);
-
-    if (enableWebpackPlugin) {
+    if (shouldEnableWebpackPlugin(buildContext, userSentryOptions)) {
       // TODO Handle possibility that user is using `SourceMapDevToolPlugin` (see
       // https://webpack.js.org/plugins/source-map-dev-tool-plugin/)
 
@@ -460,3 +450,41 @@ function ensureCLIBinaryExists(): boolean {
   }
   return false;
 }
+
+/** Check various conditions to decide if we should run the plugin */
+function shouldEnableWebpackPlugin(buildContext: BuildContext, userSentryOptions: UserSentryOptions): boolean {
+  const { isServer, dev: isDev } = buildContext;
+  const { disableServerWebpackPlugin, disableClientWebpackPlugin } = userSentryOptions;
+
+  /** Non-negotiable */
+
+  // TODO: this is a hack to fix https://github.com/getsentry/sentry-cli/issues/1085, which is caused by
+  // https://github.com/getsentry/sentry-cli/issues/915. Once the latter is addressed, this existence check can come
+  // out. (The check is necessary because currently, `@sentry/cli` uses a post-install script to download an
+  // architecture-specific version of the `sentry-cli` binary. If `yarn install`, `npm install`, or `npm ci` are run
+  // with the `--ignore-scripts` option, this will be blocked and the missing binary will cause an error when users
+  // try to build their apps.)
+  if (!ensureCLIBinaryExists()) {
+    return false;
+  }
+
+  /** User override */
+
+  if ((isServer && disableServerWebpackPlugin) || (!isServer && disableClientWebpackPlugin)) {
+    return false;
+  }
+
+  /** Situations where the default is to disable the plugin */
+
+  // TODO: Are there analogs to Vercel's preveiw and dev modes on other deployment platforms?
+
+  if (isDev || process.env.NODE_ENV === 'development') {
+    // TODO (v8): Right now in dev we set the plugin to dryrun mode, and our boilerplate includes setting the plugin to
+    // `silent`, so for the vast majority of users, it's as if the plugin doesn't run at all in dev. Making that
+    // official is technically a breaking change, though, so we probably should wait until v8.
+    // return false
+  }
+
+  // We've passed all of the tests!
+  return true;
+}