wip: remove runner on hook and then update docs

docs/guide/src/state/errorhandling.md

@@ -0,0 +1,11 @@
+# Error handling
+
+
+Astute observers might have noticed that `Element` is actually a type alias for `Option<VNode>`. You don't need to know what a `VNode` is, but it's important to recognize that we could actually return nothing at all:
+
+```rust
+fn App((cx, props): Component) -> Element {
+    None
+}
+```
+