fix(nextjs): Honor explicit spotlight option even without env var

Previously, the Spotlight integration logic was gated behind checking
if the NEXT_PUBLIC_SENTRY_SPOTLIGHT env var was set. This meant that
if a user set `spotlight: true` in Sentry.init() without the env var,
their explicit configuration was silently ignored.

Now the code always checks resolveSpotlightOptions which properly
handles both the explicit option and the env var with correct precedence.

Author: BYK

packages/nextjs/src/client/index.ts

@@ -143,23 +143,27 @@ function getDefaultIntegrations(options: BrowserOptions): Integration[] {
     }),
   );
 
-  // Add Spotlight integration if enabled via NEXT_PUBLIC_SENTRY_SPOTLIGHT env var.
-  // The env var is injected by the Next.js build config:
-  // - Webpack: valueInjectionLoader sets globalThis.NEXT_PUBLIC_SENTRY_SPOTLIGHT
-  // - Turbopack: valueInjectionLoader sets globalThis.NEXT_PUBLIC_SENTRY_SPOTLIGHT
+  // Add Spotlight integration if enabled via:
+  // 1. NEXT_PUBLIC_SENTRY_SPOTLIGHT env var (injected by Next.js build config)
+  // 2. Explicit `spotlight` option in Sentry.init()
+  //
   // We handle this in the Next.js SDK rather than the browser SDK because the browser SDK's
   // auto-detection is development-only (stripped from production builds that users install).
   const spotlightEnvValue = globalWithInjectedValues.NEXT_PUBLIC_SENTRY_SPOTLIGHT;
+
+  // Parse the env var value if present (could be 'true', 'false', or a URL)
+  let envSpotlight: boolean | string | undefined;
   if (spotlightEnvValue !== undefined) {
-    // Parse the env var value (could be 'true', 'false', or a URL)
     const boolValue = envToBool(spotlightEnvValue, { strict: true });
-    const envSpotlight = boolValue !== null ? boolValue : spotlightEnvValue;
-    const spotlightValue = resolveSpotlightOptions(options.spotlight, envSpotlight);
+    envSpotlight = boolValue !== null ? boolValue : spotlightEnvValue;
+  }
 
-    if (spotlightValue) {
-      const args = typeof spotlightValue === 'string' ? { sidecarUrl: spotlightValue } : undefined;
-      customDefaultIntegrations.push(spotlightBrowserIntegration(args));
-    }
+  // Resolve the final Spotlight config: explicit option takes precedence over env var
+  const spotlightValue = resolveSpotlightOptions(options.spotlight, envSpotlight);
+
+  if (spotlightValue) {
+    const args = typeof spotlightValue === 'string' ? { sidecarUrl: spotlightValue } : undefined;
+    customDefaultIntegrations.push(spotlightBrowserIntegration(args));
   }
 
   return customDefaultIntegrations;