Fix the fit addon

src/renderer/BackgroundRenderLayer.ts

@@ -24,6 +24,10 @@ export class BackgroundRenderLayer extends BaseRenderLayer {
   }
 
   public onGridChanged(terminal: ITerminal, startRow: number, endRow: number): void {
+    // Resize has not been called yet
+    if (this._state.cache.length === 0) {
+      return;
+    }
     for (let y = startRow; y <= endRow; y++) {
       let row = y + terminal.buffer.ydisp;
       let line = terminal.buffer.lines.get(row);

src/renderer/ForegroundRenderLayer.ts

@@ -32,6 +32,11 @@ export class ForegroundRenderLayer extends BaseRenderLayer {
     //   return;
     // }
 
+    // Resize has not been called yet
+    if (this._state.cache.length === 0) {
+      return;
+    }
+
     for (let y = startRow; y <= endRow; y++) {
       const row = y + terminal.buffer.ydisp;
       const line = terminal.buffer.lines.get(row);

src/renderer/GridCache.ts

@@ -18,7 +18,7 @@ export class GridCache<T> {
     this.cache.length = width;
   }
 
-  public clear() {
+  public clear(): void {
     for (let x = 0; x < this.cache.length; x++) {
       for (let y = 0; y < this.cache[x].length; y++) {
         this.cache[x][y] = null;