From 9db31db8861563b871a8d1160140c5614993392c Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Mon, 5 Jan 2026 11:10:56 -0800
Subject: [PATCH] Add undefined checks in erase calls

This is likely a race condition during a resize which is hard to say
what the right behavior is. Instead of hard failing by throwing an
error, silently ignore if this happens.

Fixes #5587
---
 src/common/InputHandler.ts | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/common/InputHandler.ts b/src/common/InputHandler.ts
index 1dd1640f..e0e6253c 100644
--- a/src/common/InputHandler.ts
+++ b/src/common/InputHandler.ts
@@ -1154,7 +1154,10 @@ export class InputHandler extends Disposable implements IInputHandler {
    * @param respectProtect Whether to respect the protection attribute (DECSCA).
    */
   private _eraseInBufferLine(y: number, start: number, end: number, clearWrap: boolean = false, respectProtect: boolean = false): void {
-    const line = this._activeBuffer.lines.get(this._activeBuffer.ybase + y)!;
+    const line = this._activeBuffer.lines.get(this._activeBuffer.ybase + y);
+    if (!line) {
+      return;
+    }
     line.replaceCells(
       start,
       end,
@@ -1224,7 +1227,10 @@ export class InputHandler extends Disposable implements IInputHandler {
         this._eraseInBufferLine(j, 0, this._activeBuffer.x + 1, true, respectProtect);
         if (this._activeBuffer.x + 1 >= this._bufferService.cols) {
           // Deleted entire previous line. This next line can no longer be wrapped.
-          this._activeBuffer.lines.get(j + 1)!.isWrapped = false;
+          const nextLine = this._activeBuffer.lines.get(j + 1);
+          if (nextLine) {
+            nextLine.isWrapped = false;
+          }
         }
         while (j--) {
           this._resetBufferLine(j, respectProtect);