From 8833e578f1d226ee3ae64260b755a699243cefe8 Mon Sep 17 00:00:00 2001
From: Tom Moor <tom.moor@gmail.com>
Date: Thu, 21 Sep 2023 21:16:59 -0400
Subject: [PATCH] fix: JS error hitting up or down with entire document
 selection

closes #5863
---
 shared/editor/extensions/Mermaid.ts | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/shared/editor/extensions/Mermaid.ts b/shared/editor/extensions/Mermaid.ts
index 302936cd7..a0c960113 100644
--- a/shared/editor/extensions/Mermaid.ts
+++ b/shared/editor/extensions/Mermaid.ts
@@ -205,7 +205,9 @@ export default function Mermaid({
           switch (event.key) {
             case "ArrowDown": {
               const { selection } = view.state;
-              const $pos = view.state.doc.resolve(selection.from + 1);
+              const $pos = view.state.doc.resolve(
+                Math.min(selection.from + 1, view.state.doc.nodeSize)
+              );
               const nextBlock = $pos.nodeAfter;
 
               if (
@@ -229,7 +231,9 @@ export default function Mermaid({
             }
             case "ArrowUp": {
               const { selection } = view.state;
-              const $pos = view.state.doc.resolve(selection.from - 1);
+              const $pos = view.state.doc.resolve(
+                Math.max(0, selection.from - 1)
+              );
               const prevBlock = $pos.nodeBefore;
 
               if (