Fix the fit addon

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;