feat: Fall back to NODE_ENV for Sentry Environment

Author: kamilogorek

docs/config.rst

@@ -241,4 +241,4 @@ Environment Variables
 
 .. describe:: SENTRY_ENVIRONMENT
 
-    Optionally set the environment name, e.g. "staging", "production".
+    Optionally set the environment name, e.g. "staging", "production". Sentry will default to the value of `NODE_ENV`, if present.

lib/client.js

@@ -54,7 +54,8 @@ extend(Raven.prototype, {
     this.transport = options.transport || transports[this.dsn.protocol];
     this.sendTimeout = options.sendTimeout || 1;
     this.release = options.release || process.env.SENTRY_RELEASE || '';
-    this.environment = options.environment || process.env.SENTRY_ENVIRONMENT || '';
+    this.environment =
+      options.environment || process.env.SENTRY_ENVIRONMENT || process.env.NODE_ENV || '';
 
     // autoBreadcrumbs: true enables all, autoBreadcrumbs: false disables all
     // autoBreadcrumbs: { http: true } enables a single type