fix: ensure process is defined

Author: faraazb-contentstack

src/index.ts

@@ -71,8 +71,9 @@ class LightLivePreviewHoC {
 }
 
 const ContentstackLivePreview =
-    process?.env?.PURGE_PREVIEW_SDK === "true" ||
-    process?.env?.REACT_APP_PURGE_PREVIEW_SDK === "true"
+    typeof process !== "undefined" &&
+    (process?.env?.PURGE_PREVIEW_SDK === "true" ||
+        process?.env?.REACT_APP_PURGE_PREVIEW_SDK === "true")
         ? LightLivePreviewHoC
         : ContentstackLivePreviewHOC;