Add panic-handlers which exit on any panic

By default, tokio-spawned worker panics will only kill the task, not the
program. Due to our extensive use of panicking on invariants, we should ensure
the program exits.

processor/src/main.rs

@@ -726,6 +726,18 @@ async fn run<N: Network, D: Db, Co: Coordinator>(mut raw_db: D, network: N, mut
 
 #[tokio::main]
 async fn main() {
+  // Override the panic handler with one which will panic if any tokio task panics
+  {
+    let existing = std::panic::take_hook();
+    std::panic::set_hook(Box::new(move |panic| {
+      existing(panic);
+      const MSG: &str = "exiting the process due to a task panicking";
+      println!("{MSG}");
+      log::error!("{MSG}");
+      std::process::exit(1);
+    }));
+  }
+
   if std::env::var("RUST_LOG").is_err() {
     std::env::set_var("RUST_LOG", serai_env::var("RUST_LOG").unwrap_or_else(|| "info".to_string()));
   }