fix ECH

src/InputHandler.test.ts

@@ -1048,6 +1048,20 @@ describe('InputHandler', () => {
         term.writeSync('0123456789\x1b[P');
         assert.equal(term.buffer.lines.get(0).translateToString(false), '012345678 ');
       });
+      it('ECH', () => {
+        term.buffer.x = 10000;
+        term.buffer.y = 10000;
+        term.writeSync('\x1b[X');
+        assert.deepEqual(getCursor(term), [9, 9]);
+        term.buffer.x = -10000;
+        term.buffer.y = -10000;
+        term.writeSync('\x1b[X');
+        assert.deepEqual(getCursor(term), [0, 0]);
+      });
+      it('ECH - should delete last cell', () => {
+        term.writeSync('0123456789\x1b[X');
+        assert.equal(term.buffer.lines.get(0).translateToString(false), '012345678 ');
+      });
     });
   });
 });

src/InputHandler.ts

@@ -950,12 +950,16 @@ export class InputHandler extends Disposable implements IInputHandler {
    * Erase Ps Character(s) (default = 1) (ECH).
    */
   public eraseChars(params: IParams): void {
-    this._terminal.buffer.lines.get(this._terminal.buffer.y + this._terminal.buffer.ybase).replaceCells(
-      this._terminal.buffer.x,
-      this._terminal.buffer.x + (params.params[0] || 1),
-      this._terminal.buffer.getNullCell(this._terminal.eraseAttrData())
-    );
-    this._terminal.updateRange(this._terminal.buffer.y);
+    this._restrictCursor();
+    const line = this._terminal.buffer.lines.get(this._terminal.buffer.y + this._terminal.buffer.ybase);
+    if (line) {
+      line.replaceCells(
+        this._terminal.buffer.x,
+        this._terminal.buffer.x + (params.params[0] || 1),
+        this._terminal.buffer.getNullCell(this._terminal.eraseAttrData())
+      );
+      this._terminal.updateRange(this._terminal.buffer.y);
+    }
   }
 
   /**