From 5e697b348c0336d11a64ce0440aed6c40b104f1c Mon Sep 17 00:00:00 2001
From: rebornix <penn.lv@gmail.com>
Date: Mon, 10 Aug 2020 13:30:53 -0700
Subject: [PATCH] fix #104397.

---
 .../contrib/notebook/browser/view/notebookCellList.ts  | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts b/src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts
index 687a666c773..6a257986a44 100644
--- a/src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts
+++ b/src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts
@@ -398,6 +398,10 @@ export class NotebookCellList extends WorkbenchList<CellViewModel> implements ID
 		const viewIndexInfo = this.hiddenRangesPrefixSum.getIndexOf(modelIndex);
 
 		if (viewIndexInfo.remainder !== 0) {
+			if (modelIndex >= this.hiddenRangesPrefixSum.getTotalValue()) {
+				// it's already after the last hidden range
+				return modelIndex - (this.hiddenRangesPrefixSum.getTotalValue() - this.hiddenRangesPrefixSum.getCount());
+			}
 			return undefined;
 		} else {
 			return viewIndexInfo.index;
@@ -413,6 +417,12 @@ export class NotebookCellList extends WorkbenchList<CellViewModel> implements ID
 
 		const viewIndexInfo = this.hiddenRangesPrefixSum.getIndexOf(modelIndex);
 
+		if (viewIndexInfo.remainder !== 0) {
+			if (modelIndex >= this.hiddenRangesPrefixSum.getTotalValue()) {
+				return modelIndex - (this.hiddenRangesPrefixSum.getTotalValue() - this.hiddenRangesPrefixSum.getCount());
+			}
+		}
+
 		return viewIndexInfo.index;
 	}