Example: How to connect to parachain (#1043)

* parachain rpc lists

* guide almost done

* add the 3rd config

* subscribe to block with configs

* delete table file

* spaces instead of tabs

* remove original ajuna example

* zombienet setup

* nft minting example

* include port, use different names

* link the example from the book

* format book

* add config creation to book, simplify example structure

* fix the nft creation script

* fix doc ref

* fixing links to foreign crates

* fix table formatting

* include nits

* move more docs to book, and simplify parachain-example

* another pass over docs and link to exampels from guide

* nit: adjust comment to numbers

* teeny README fix for parachain-example

* fix command in readme

* add CI for examples and fix parachain-example bug I left in

* add target arch

* cargo fmt

* make CI not fail

* remove index from docs

---------

Co-authored-by: James Wilson <james@jsdw.me>

subxt/src/client/online_client.rs

@@ -468,7 +468,7 @@ mod jsonrpsee_helpers {
 }
 
 // helpers for a jsonrpsee specific OnlineClient.
-#[cfg(all(feature = "jsonrpsee", feature = "web"))]
+#[cfg(all(feature = "jsonrpsee", feature = "web", target_arch = "wasm32"))]
 mod jsonrpsee_helpers {
     pub use jsonrpsee::{
         client_transport::web,
@@ -480,7 +480,9 @@ mod jsonrpsee_helpers {
 
     /// Build web RPC client from URL
     pub async fn client(url: &str) -> Result<Client, Error> {
-        let (sender, receiver) = web::connect(url).await.unwrap();
+        let (sender, receiver) = web::connect(url)
+            .await
+            .map_err(|e| Error::Transport(e.into()))?;
         Ok(ClientBuilder::default()
             .max_notifs_per_subscription(4096)
             .build_with_wasm(sender, receiver))