From c20580f90e3e478eb59041929fc269698789ba4a Mon Sep 17 00:00:00 2001
From: Jim Fisher <jameshfisher@gmail.com>
Date: Wed, 5 Jan 2022 19:05:21 +0000
Subject: [PATCH] Warn when normalization removes node

Slate requires the invariant that children are all blocks or all inlines.
It enforces this in default normalization by removing children.
When such a node is removed, it's almost certainly due to a programming
error: the developer needs to fix their application to ensure it
maintains this invariant. But currently Slate does not tell the
developer this.

I made such a programming error, and spent a long time debugging nodes
that mysteriously went missing. I would have fixed it within 30 seconds
if Slate had warned me when it detected this error.

(Note I have used console.warn despite the eslint rule. As far as I can
see, Slate has no other facility for runtime warnings.)
---
 packages/slate/src/create-editor.ts | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/packages/slate/src/create-editor.ts b/packages/slate/src/create-editor.ts
index b1a903b5eb6..f6f2a36de18 100644
--- a/packages/slate/src/create-editor.ts
+++ b/packages/slate/src/create-editor.ts
@@ -227,7 +227,16 @@ export const createEditor = (): Editor => {
         // other inline nodes, or parent blocks that only contain inlines and
         // text.
         if (isInlineOrText !== shouldHaveInlines) {
-          Transforms.removeNodes(editor, { at: path.concat(n), voids: true })
+          // eslint-disable-next-line no-console
+          console.warn(
+            `Removing ${
+              isInlineOrText ? 'inline' : 'block'
+            } node at path ${path.concat(n)} because parent expects ${
+              shouldHaveInlines ? 'inline' : 'block'
+            } children`
+          )
+          const removePath = path.concat(n)
+          Transforms.removeNodes(editor, { at: removePath, voids: true })
           n--
         } else if (Element.isElement(child)) {
           // Ensure that inline nodes are surrounded by text nodes.