diff --git a/src/components/Modal.svelte b/src/components/Modal.svelte
index 72320a1..beb2cf2 100644
--- a/src/components/Modal.svelte
+++ b/src/components/Modal.svelte
@@ -1,7 +1,7 @@
 <script lang="ts">
   export let onClose: () => void;
 
-  function click(event: Event) {
+  function click(this: Element, event: Event) {
     if (event.target !== this) return;
     onClose();
   }
diff --git a/src/components/PagePicker.svelte b/src/components/PagePicker.svelte
index fa81cd1..cfe9b58 100644
--- a/src/components/PagePicker.svelte
+++ b/src/components/PagePicker.svelte
@@ -1,5 +1,4 @@
 <script lang="ts">
-  import type { Readable } from "svelte/store";
   import { yDocToProsemirrorJSON } from "y-prosemirror";
   import { Node } from "prosemirror-model";
   import type { Doc } from "yjs";
@@ -29,7 +28,7 @@
           }
         });
         docs.push({
-          title: titleNode?.textContent,
+          title: titleNode ? (titleNode as Node).textContent : undefined,
           id: name.replace(/^page\//, ""),
           name,
         });
@@ -45,7 +44,7 @@
   $: entries = deriveEntries(ydoc);
   $: lastU = lastUpdated(ydoc);
   $: sortedEntries = $entries
-    .sort((a, b) => +$lastU.get(b.name) - +$lastU.get(a.name))
+    .sort((a, b) => +($lastU.get(b.name) || 0) - +($lastU.get(a.name) || 0))
     // TODO: FTS
     .filter((x) => (x.title ?? x.id).includes(filter));
   // $: console.debug($lastU);
diff --git a/src/editor/BubbleMenu.svelte b/src/editor/BubbleMenu.svelte
index a3c689a..be7ffb0 100644
--- a/src/editor/BubbleMenu.svelte
+++ b/src/editor/BubbleMenu.svelte
@@ -19,7 +19,6 @@
     getFirstMarkInSelection,
   } from "./ps-utils";
   import SimpleMarkItem from "./bubblemenu/SimpleMarkItem.svelte";
-  import { nanoid } from "nanoid";
   import Button from "./bubblemenu/Button.svelte";
   import Modal from "../components/Modal.svelte";
   import PagePicker from "../components/PagePicker.svelte";
@@ -105,7 +104,7 @@
   /* https://wicg.github.io/visual-viewport/examples/fixed-to-keyboard.html */
   let barStyle = "";
   function updateBar() {
-    const viewport = window.visualViewport;
+    const viewport = window.visualViewport!;
     // Since the bar is position: fixed we need to offset it by the
     // visual viewport's offset from the layout viewport origin.
     const offsetY = window.innerHeight - viewport.height - viewport.offsetTop;
@@ -118,12 +117,12 @@ transform: scale(${1 / viewport.scale});
   }
 
   onMount(() => {
-    window.visualViewport.addEventListener("resize", updateBar);
-    window.visualViewport.addEventListener("scroll", updateBar);
+    window.visualViewport!.addEventListener("resize", updateBar);
+    window.visualViewport!.addEventListener("scroll", updateBar);
   });
   onDestroy(() => {
-    window.visualViewport.removeEventListener("resize", updateBar);
-    window.visualViewport.removeEventListener("scroll", updateBar);
+    window.visualViewport!.removeEventListener("resize", updateBar);
+    window.visualViewport!.removeEventListener("scroll", updateBar);
   });
 </script>
 
diff --git a/src/editor/Editor.svelte b/src/editor/Editor.svelte
index 4051cb8..6b855e8 100644
--- a/src/editor/Editor.svelte
+++ b/src/editor/Editor.svelte
@@ -5,14 +5,14 @@
   import { dropCursor } from "prosemirror-dropcursor";
   import { gapCursor } from "prosemirror-gapcursor";
   import type { XmlFragment } from "yjs";
-  import { ySyncPlugin, yCursorPlugin, yUndoPlugin } from "y-prosemirror";
+  import { ySyncPlugin, yUndoPlugin } from "y-prosemirror";
 
   import "./editor.css";
 
   import { schema } from "./schema";
   import BubbleMenu from "./BubbleMenu.svelte";
   import MenuBar from "./MenuBar.svelte";
-  import { placeholderPlugin } from "./upload";
+  // import { placeholderPlugin } from "./upload";
   import { baseKeymap } from "./keymap";
   import type { WorldY } from "../lib/doc";
 
@@ -26,7 +26,7 @@
       schema,
       plugins: [
         new Plugin({
-          view: (editorView) => {
+          view: () => {
             // editorView.dom.parentElement?.replaceWith(editorView.dom);
             return {
               update(view, lastState) {
@@ -50,7 +50,7 @@
         // yCursorPlugin(doc.webrtcProvider.awareness),
         yUndoPlugin(),
         keymap(baseKeymap),
-        placeholderPlugin,
+        // placeholderPlugin,
       ],
     });
   }
diff --git a/src/editor/menubar/BlockQuoteItem.svelte b/src/editor/menubar/BlockQuoteItem.svelte
index f80d221..0441de1 100644
--- a/src/editor/menubar/BlockQuoteItem.svelte
+++ b/src/editor/menubar/BlockQuoteItem.svelte
@@ -15,7 +15,7 @@
 
   $: isActive = nodeIsActiveFn(type, null, true);
   $: command = wrapIn(type);
-  $: isPossible = command(state, null);
+  $: isPossible = command(state);
   $: actionListener = commandListener(view, command);
 </script>
 
diff --git a/src/editor/menubar/BlockSelect.svelte b/src/editor/menubar/BlockSelect.svelte
index 9b75423..240c828 100644
--- a/src/editor/menubar/BlockSelect.svelte
+++ b/src/editor/menubar/BlockSelect.svelte
@@ -10,7 +10,7 @@
   const paragraphType = state.schema.nodes.paragraph;
   const headingType = state.schema.nodes.heading;
 
-  $: isPossible = setBlockType(headingType, { level: 1 })(state, null);
+  $: isPossible = setBlockType(headingType, { level: 1 })(state);
   $: currentValue =
     state.selection.to <= state.selection.$from.end() &&
     (state.selection.$from.parent.type == headingType
@@ -19,10 +19,12 @@
       ? "paragraph"
       : null);
 
-  const onChange = (event) => {
+  const onChange = (
+    event: Event & { currentTarget: EventTarget & HTMLSelectElement }
+  ) => {
     event.preventDefault();
 
-    const [type, param] = event.target.value.split(":");
+    const [type, param] = event.currentTarget.value.split(":");
     if (type === "paragraph") {
       setBlockType(paragraphType, {
         align: state.selection.$from.parent.attrs.align,
diff --git a/src/editor/menubar/ListItem.svelte b/src/editor/menubar/ListItem.svelte
index f90d73a..db6bc68 100644
--- a/src/editor/menubar/ListItem.svelte
+++ b/src/editor/menubar/ListItem.svelte
@@ -21,7 +21,7 @@
       ? state.schema.nodes.bullet_list
       : kind === ListKind.Ordered
       ? state.schema.nodes.ordered_list
-      : null;
+      : (null as never);
   const listItemType = state.schema.nodes.list_item;
   $: iconComponent =
     kind === ListKind.Unordered
@@ -32,7 +32,7 @@
 
   $: isActive = nodeIsActiveFn(type, null, true);
   $: command = chainCommands(liftListItem(listItemType), wrapInList(type));
-  $: isPossible = command(state, null);
+  $: isPossible = command(state);
   $: actionListener = commandListener(view, command);
 </script>
 
diff --git a/src/editor/menubar/UploadItem.svelte b/src/editor/menubar/UploadItem.sveltehold
similarity index 100%
rename from src/editor/menubar/UploadItem.svelte
rename to src/editor/menubar/UploadItem.sveltehold
diff --git a/src/editor/ps-utils.ts b/src/editor/ps-utils.ts
index 06381d1..7ef25f7 100644
--- a/src/editor/ps-utils.ts
+++ b/src/editor/ps-utils.ts
@@ -6,11 +6,9 @@ import type {
   ResolvedPos,
   Node as ProsemirrorNode,
 } from "prosemirror-model";
-import type { EditorState, Selection } from "prosemirror-state";
+import type { EditorState } from "prosemirror-state";
 import type { EditorView } from "prosemirror-view";
 
-import type { Align } from "./schema";
-
 export type Command = (
   state: EditorState,
   dispatch?: EditorView["dispatch"]
@@ -176,7 +174,7 @@ export function getAttrFn(attrKey: string): (state: EditorState) => any {
   return (state) => {
     let { from, to } = state.selection;
     let value: any = undefined;
-    state.doc.nodesBetween(from, to, (node, pos) => {
+    state.doc.nodesBetween(from, to, (node) => {
       if (value !== undefined) return false;
       if (!node.isTextblock) return;
       if (attrKey in node.attrs) value = node.attrs[attrKey];
@@ -199,10 +197,10 @@ export interface MarkMatch {
 export function getFirstMarkInSelection(
   state: EditorState,
   type: MarkType
-): MarkMatch {
+): MarkMatch | null {
   const { to, from } = state.selection;
 
-  let match: MarkMatch;
+  let match: MarkMatch | null = null;
   state.selection.$from.doc.nodesBetween(from, to, (node, position) => {
     if (!match) {
       const mark = type.isInSet(node.marks);
@@ -213,25 +211,3 @@ export function getFirstMarkInSelection(
 
   return match;
 }
-
-export function setAlign(align: Align): Command {
-  return (state, dispatch) => {
-    let { from, to } = state.selection;
-    let node: ProsemirrorNode | null = null;
-    state.doc.nodesBetween(from, to, (_node, pos) => {
-      if (node) return false;
-      if (!_node.isTextblock) return;
-      if (
-        _node.type == state.schema.nodes.paragraph ||
-        _node.type == state.schema.nodes.heading
-      ) {
-        node = _node;
-      }
-    });
-    if (!node) return false;
-    if (dispatch)
-      return setBlockType(node.type, { ...node.attrs, align })(state, dispatch);
-
-    return true;
-  };
-}
diff --git a/src/editor/schema.ts b/src/editor/schema.ts
index 3d37862..5c137dc 100644
--- a/src/editor/schema.ts
+++ b/src/editor/schema.ts
@@ -101,8 +101,9 @@ export const schema = new Schema({
           tag: "ol",
           getAttrs(dom) {
             dom = dom as HTMLElement;
+            const start = dom.getAttribute("start");
             return {
-              order: dom.hasAttribute("start") ? +dom.getAttribute("start") : 1,
+              order: start ? +start : 1,
             };
           },
         },
@@ -141,11 +142,12 @@ export const schema = new Schema({
         {
           tag: "figure",
           getAttrs(dom) {
-            const child: HTMLElement =
+            const child: HTMLElement | null =
               (dom as Element).querySelector("img") ||
               (dom as Element).querySelector("video") ||
               (dom as Element).querySelector("audio") ||
               (dom as Element).querySelector("iframe");
+            if (!child) return false;
 
             if (child instanceof HTMLImageElement) {
               return { src: child.src, kind: "img" };
@@ -156,6 +158,7 @@ export const schema = new Schema({
             } else if (child instanceof HTMLIFrameElement) {
               return { src: child.src, kind: "iframe" };
             }
+            return false;
           },
         },
         {
@@ -308,9 +311,11 @@ export const schema = new Schema({
           getAttrs(dom) {
             dom = dom as HTMLElement;
             const href = dom.getAttribute("href");
-            if (href.startsWith("/w/")) {
+            if (href?.startsWith("/w/")) {
+              const matches = parse(routes.Page).pattern.exec(href);
+              if (!matches) return false;
               return {
-                id: parse(routes.Page).pattern.exec(href)[1],
+                id: matches[1],
               };
             } else return false;
           },
diff --git a/src/editor/upload.ts b/src/editor/upload.tshold
similarity index 87%
rename from src/editor/upload.ts
rename to src/editor/upload.tshold
index d394726..c86f756 100644
--- a/src/editor/upload.ts
+++ b/src/editor/upload.tshold
@@ -42,7 +42,7 @@ export const placeholderPlugin = new Plugin({
 });
 
 export function findPlaceholder(state: EditorState, id: any): number | null {
-  const decos: DecorationSet = placeholderPlugin.getState(state);
-  const found = decos.find(undefined, undefined, (spec) => spec.id == id);
-  return found.length ? found[0].from : null;
+  const decos = placeholderPlugin.getState(state);
+  const found = decos?.find(undefined, undefined, (spec) => spec.id == id);
+  return found?.length ? found[0].from : null;
 }
diff --git a/src/lib/makeYdocStore.ts b/src/lib/makeYdocStore.ts
index 424ecfd..7d527f2 100644
--- a/src/lib/makeYdocStore.ts
+++ b/src/lib/makeYdocStore.ts
@@ -2,7 +2,12 @@ import type { Readable } from "svelte/store";
 import type { Doc, Transaction } from "yjs";
 
 export function makeYdocStore<T>(
-  handler: (update: Uint8Array, origin: any, ydoc: Doc, tr: Transaction) => T,
+  handler: (
+    update: Uint8Array | null,
+    origin: any,
+    ydoc: Doc,
+    tr: Transaction | null
+  ) => T,
   unhandler?: () => void
 ) {
   return (ydoc: Doc): Readable<T> => {
@@ -10,10 +15,10 @@ export function makeYdocStore<T>(
     return {
       subscribe: (run) => {
         function updateHandler(
-          update: Uint8Array,
+          update: Uint8Array | null,
           origin: any,
           ydoc: Doc,
-          tr: Transaction
+          tr: Transaction | null
         ) {
           run(handler(update, origin, ydoc, tr));
         }
diff --git a/src/main.ts b/src/main.ts
index 8a909a1..e736285 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,8 +1,8 @@
-import './app.css'
-import App from './App.svelte'
+import "./app.css";
+import App from "./App.svelte";
 
 const app = new App({
-  target: document.getElementById('app'),
-})
+  target: document.getElementById("app")!,
+});
 
-export default app
+export default app;
diff --git a/src/views/CreateWorld.svelte b/src/views/CreateWorld.svelte
index 3d1efae..42ef5df 100644
--- a/src/views/CreateWorld.svelte
+++ b/src/views/CreateWorld.svelte
@@ -4,11 +4,7 @@
   import { router } from "../lib/router";
   import { writeWorlds } from "../lib/worldStorage";
 
-  function crear(
-    event: Event & { readonly submitter: HTMLElement } & {
-      currentTarget: EventTarget & HTMLFormElement;
-    }
-  ) {
+  function crear(event: Event) {
     event.preventDefault();
     writeWorlds((worlds) => [...worlds, generateNewWorld()]);
     router.run(routes.ChooseWorld);
diff --git a/src/views/ShareWorld.svelte b/src/views/ShareWorld.svelte
index 9cd7ff8..8278a44 100644
--- a/src/views/ShareWorld.svelte
+++ b/src/views/ShareWorld.svelte
@@ -8,6 +8,7 @@
   async function joinWorldLink() {
     const worlds = await loadWorlds();
     const worldIdentifier = worlds.find((w) => w.room === worldId);
+    if (!worldIdentifier) throw new Error("No tenés ese mundo para compartir.");
     return `${location.origin}${inject(routes.JoinWorld, {
       worldId: worldIdentifier.room,
     })}#${worldIdentifier.password}`;
diff --git a/tsconfig.json b/tsconfig.json
index c4e1c5f..f52d57a 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -13,6 +13,7 @@
      */
     "allowJs": true,
     "checkJs": true,
+    "strict": true,
     "isolatedModules": true
   },
   "include": ["src/**/*.d.ts", "src/**/*.ts", "src/**/*.js", "src/**/*.svelte"],