fix(core): Always re-initialize native SDK from JS in dev builds (#5872)

When `sentry.options.json` exists (generated by the Expo config plugin
with `useNativeInit: true`), the SDK was setting
`autoInitializeNativeSdk = false`, skipping the JS-side `initNativeSdk`
call entirely. This prevented the native log bridge and runtime values
(devServerUrl, defaultSidecarUrl) from being set up, causing zero
envelopes to be sent to sentry.io in development builds.

The fix adds a `!__DEV__` guard so that in dev builds, JS always
re-initializes native (the native SDK handles double-init gracefully
with "Previous configuration will be overwritten"). In release builds,
the existing behavior is preserved for app start crash capture.

Closes #5734

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antonis

packages/core/src/js/sdk.tsx

@@ -140,9 +140,11 @@ export function init(passedOptions: ReactNativeOptions): void {
     initialScope: safeFactory(userOptions.initialScope, { loggerMessage: 'The initialScope threw an error' }),
   };
 
-  if (!('autoInitializeNativeSdk' in userOptions) && RN_GLOBAL_OBJ.__SENTRY_OPTIONS__) {
-    // Options file is present, native SDK is expected to be initialized
+  if (!('autoInitializeNativeSdk' in userOptions) && RN_GLOBAL_OBJ.__SENTRY_OPTIONS__ && !__DEV__) {
+    // Options file is present in a release build, native SDK is expected to be initialized
     // before JS from the native app entry point (e.g. AppDelegate, MainApplication).
+    // In dev builds, we always re-initialize from JS to set up the native log bridge
+    // and provide runtime values (devServerUrl, defaultSidecarUrl, etc.).
     // eslint-disable-next-line no-console
     console.info('[Sentry] Using options file. Native SDK is expected to be initialized before JS, skipping automatic native initialization from JS.');
     options.autoInitializeNativeSdk = false;

packages/core/test/sdk.test.ts

@@ -135,10 +135,34 @@ describe('Tests the SDK functionality', () => {
         expect(usedOptions()?.dsn).toBe('https://key@example.io/code');
       });
 
-      it('initializing with __SENTRY_OPTIONS__ disabled native auto initialization', () => {
-        RN_GLOBAL_OBJ.__SENTRY_OPTIONS__ = {};
-        init({});
-        expect(usedOptions()?.autoInitializeNativeSdk).toBe(false);
+      it('does not disable native auto initialization in dev builds even with __SENTRY_OPTIONS__', () => {
+        // @ts-expect-error __DEV__ is a global
+        const originalDev = globalThis.__DEV__;
+        // @ts-expect-error __DEV__ is a global
+        globalThis.__DEV__ = true;
+        try {
+          RN_GLOBAL_OBJ.__SENTRY_OPTIONS__ = {};
+          init({});
+          expect(usedOptions()?.autoInitializeNativeSdk).toBe(true);
+        } finally {
+          // @ts-expect-error __DEV__ is a global
+          globalThis.__DEV__ = originalDev;
+        }
+      });
+
+      it('disables native auto initialization in release builds with __SENTRY_OPTIONS__', () => {
+        // @ts-expect-error __DEV__ is a global
+        const originalDev = globalThis.__DEV__;
+        // @ts-expect-error __DEV__ is a global
+        globalThis.__DEV__ = false;
+        try {
+          RN_GLOBAL_OBJ.__SENTRY_OPTIONS__ = {};
+          init({});
+          expect(usedOptions()?.autoInitializeNativeSdk).toBe(false);
+        } finally {
+          // @ts-expect-error __DEV__ is a global
+          globalThis.__DEV__ = originalDev;
+        }
       });
 
       it('initializing without __SENTRY_OPTIONS__ enables native auto initialization', () => {
@@ -155,7 +179,7 @@ describe('Tests the SDK functionality', () => {
         expect(usedOptions()?.autoInitializeNativeSdk).toBe(true);
       });
 
-      it('initializing with __SENTRY_OPTIONS__ keeps native auto initialization false if set', () => {
+      it('respects explicit autoInitializeNativeSdk false even with __SENTRY_OPTIONS__', () => {
         RN_GLOBAL_OBJ.__SENTRY_OPTIONS__ = {};
         init({
           autoInitializeNativeSdk: false,