From aaa694da9b8928cda53125598159817c776b5e9c Mon Sep 17 00:00:00 2001
From: Henrik Wenz <henrik.wenz@gmail.com>
Date: Wed, 8 Aug 2018 15:13:20 +0200
Subject: [PATCH] Throw error if getInitialProps is defined as as instance
 method

Omitting the static keyword happens pretty often. Therefore we should trigger a warning in devmode.

Closes: #4782
---
 lib/utils.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/utils.js b/lib/utils.js
index 22faec6a62f2a..2474870175c41 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -54,6 +54,14 @@ export function isResSent (res) {
 }
 
 export async function loadGetInitialProps (Component, ctx) {
+  if (process.env.NODE_ENV !== 'production') {
+    if (Component.prototype && Component.prototype.getInitialProps) {
+      const compName = getDisplayName(Component)
+      const message = `"${compName}.getInitialProps()" is defined as an instance method.`
+      throw new Error(message)
+    }
+  }
+
   if (!Component.getInitialProps) return {}
 
   const props = await Component.getInitialProps(ctx)