fix broken terminal

src/vs/workbench/parts/terminal/electron-browser/terminalInstance.ts

@@ -511,14 +511,16 @@ export class TerminalInstance implements ITerminalInstance {
 			// background since scrollTop changes take no effect but the terminal's position does
 			// change since the number of visible rows decreases.
 			this._xterm.emit('scroll', this._xterm.buffer.ydisp);
-			// Force a layout when the instance becomes invisible. This is particularly important
-			// for ensuring that terminals that are created in the background by an extension will
-			// correctly get correct character measurements in order to render to the screen (see
-			// #34554).
-			const computedStyle = window.getComputedStyle(this._container);
-			const width = parseInt(computedStyle.getPropertyValue('width').replace('px', ''), 10);
-			const height = parseInt(computedStyle.getPropertyValue('height').replace('px', ''), 10);
-			this.layout(new Dimension(width, height));
+			if (this._container) {
+				// Force a layout when the instance becomes invisible. This is particularly important
+				// for ensuring that terminals that are created in the background by an extension will
+				// correctly get correct character measurements in order to render to the screen (see
+				// #34554).
+				const computedStyle = window.getComputedStyle(this._container);
+				const width = parseInt(computedStyle.getPropertyValue('width').replace('px', ''), 10);
+				const height = parseInt(computedStyle.getPropertyValue('height').replace('px', ''), 10);
+				this.layout(new Dimension(width, height));
+			}
 		}
 	}