Fix error in alternative JS environments (#2500)

Author: Jarred-Sumner

.changeset/hip-cherries-arrive.md

@@ -0,0 +1,5 @@
+---
+'@emotion/react': patch
+---
+
+Fix error loading @emotion/react in alternative JS environments

packages/react/src/index.js

@@ -20,7 +20,14 @@ if (process.env.NODE_ENV !== 'production') {
   const isJest = typeof jest !== 'undefined'
 
   if (isBrowser && !isJest) {
-    const globalContext = isBrowser ? window : global
+    // globalThis has wide browser support - https://caniuse.com/?search=globalThis, Node.js 12 and later
+    const globalContext =
+      // $FlowIgnore
+      typeof globalThis !== 'undefined'
+        ? globalThis // eslint-disable-line no-undef
+        : isBrowser
+        ? window
+        : global
     const globalKey = `__EMOTION_REACT_${pkg.version.split('.')[0]}__`
     if (globalContext[globalKey]) {
       console.warn(