Clear state when resizing as canvases get cleared

src/renderer/ForegroundRenderLayer.ts

@@ -16,6 +16,8 @@ export class ForegroundRenderLayer extends BaseRenderLayer {
 
   public resize(terminal: ITerminal, canvasWidth: number, canvasHeight: number, charSizeChanged: boolean): void {
     super.resize(terminal, canvasWidth, canvasHeight, charSizeChanged);
+    // Resizing the canvas discards the contents of the canvas so clear state
+    this._state.clear();
     this._state.resize(terminal.cols, terminal.rows);
   }