From 2a0843349c9405c6710d11c75cbbf926afcfb79a Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Wed, 19 Feb 2020 00:20:45 -0600
Subject: [PATCH] Update error message for invalid return value from
 getStaticPaths (#10580)

---
 packages/next/build/utils.ts | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/packages/next/build/utils.ts b/packages/next/build/utils.ts
index 5f76e1d087b97b5..8d6aeeb096d3376 100644
--- a/packages/next/build/utils.ts
+++ b/packages/next/build/utils.ts
@@ -562,9 +562,15 @@ export async function isPageStatic(
 
       const staticPathsResult = await (mod.unstable_getStaticPaths as Unstable_getStaticPaths)()
 
-      if (!staticPathsResult || typeof staticPathsResult !== 'object') {
+      const expectedReturnVal = `Expected: { paths: [] }`
+
+      if (
+        !staticPathsResult ||
+        typeof staticPathsResult !== 'object' ||
+        Array.isArray(staticPathsResult)
+      ) {
         throw new Error(
-          `Invalid value returned from unstable_getStaticPaths in ${page}. Received ${typeof staticPathsResult} Expected: { paths: [] }`
+          `Invalid value returned from unstable_getStaticPaths in ${page}. Received ${typeof staticPathsResult} ${expectedReturnVal}`
         )
       }
 
@@ -576,7 +582,7 @@ export async function isPageStatic(
         throw new Error(
           `Extra keys returned from unstable_getStaticPaths in ${page} (${invalidStaticPathKeys.join(
             ', '
-          )}) The only field allowed currently is \`paths\``
+          )}) ${expectedReturnVal}`
         )
       }