diff --git a/frontend/main.js b/frontend/main.js
index 1741109..142148f 100644
--- a/frontend/main.js
+++ b/frontend/main.js
@@ -20,6 +20,7 @@ class Backend {
     this.config.makeMove(move);
   }
   getAvailableMoves(position) {
+    position;
     return [];
   }
 }
@@ -39,7 +40,9 @@ class Chess {
     this.configVis.configuration = config;
     this.configVis.draw(this.canvas);
   }
-  showAvailableMoves(canMoveTo) {}
+  showAvailableMoves(canMoveTo) {
+    canMoveTo;
+  }
   click(ev) {
     if (this.moveSource === null) {
       this._firstClick(ev);
@@ -68,21 +71,6 @@ class Chess {
   }
 }
 
-class Move {
-  constructor(kind, from, to) {
-    this.kind = kind;
-    this.from = from;
-    this.to = to;
-  }
-}
-
-class Piece {
-  constructor(piece_type, color) {
-    this.piece_type = piece_type;
-    this.color = color;
-  }
-}
-
 class Configuration {
   constructor(board) {
     this.board = new Map(board);
diff --git a/frontend/visuals.js b/frontend/visuals.js
index 6fdebdf..3742fce 100644
--- a/frontend/visuals.js
+++ b/frontend/visuals.js
@@ -142,7 +142,7 @@ export class ConfigVis {
     }
   }
   undraw() {
-    for (let [position, pv] of this.piecesVis) {
+    for (let pv of this.piecesVis.values()) {
       pv.undraw();
     }
     this.piecesVis.clear();