add env check before warning

Author: ktsn

src/data.ts

@@ -25,11 +25,13 @@ export function collectDataFromConstructor (vm: Vue, Component: VueClass) {
     }
   })
 
-  if (!(Component.prototype instanceof Vue) && Object.keys(plainData).length > 0) {
-    warn(
-      'Component class must inherit Vue or its descendant class ' +
-      'when class property is used.'
-    )
+  if (process.env.NODE_ENV !== 'production') {
+    if (!(Component.prototype instanceof Vue) && Object.keys(plainData).length > 0) {
+      warn(
+        'Component class must inherit Vue or its descendant class ' +
+        'when class property is used.'
+      )
+    }
   }
 
   return plainData

src/globals.d.ts

@@ -0,0 +1,10 @@
+/**
+ * global type declarations in this project
+ * should not expose to userland
+ */
+
+declare const process: {
+  env: {
+    NODE_ENV: string
+  }
+}