From ad7f6d4510afc71ed40da1aa1ad649d59d3aef12 Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Wed, 14 Apr 2021 23:11:39 +0200
Subject: [PATCH] fix(core): better "missing type" GothamState error (#10189)

Include the type name in the error message so you know what to look for.
---
 core/gotham_state.rs | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/core/gotham_state.rs b/core/gotham_state.rs
index b8f42137f5..4da8ac2786 100644
--- a/core/gotham_state.rs
+++ b/core/gotham_state.rs
@@ -4,6 +4,7 @@
 // Copyright 2017 Gotham Project Developers. MIT license.
 
 use log::trace;
+use std::any::type_name;
 use std::any::Any;
 use std::any::TypeId;
 use std::collections::BTreeMap;
@@ -38,9 +39,7 @@ impl GothamState {
 
   /// Borrows a value from the `GothamState` storage.
   pub fn borrow<T: 'static>(&self) -> &T {
-    self
-      .try_borrow()
-      .expect("required type is not present in GothamState container")
+    self.try_borrow().unwrap_or_else(|| missing::<T>())
   }
 
   /// Tries to mutably borrow a value from the `GothamState` storage.
@@ -52,9 +51,7 @@ impl GothamState {
 
   /// Mutably borrows a value from the `GothamState` storage.
   pub fn borrow_mut<T: 'static>(&mut self) -> &mut T {
-    self
-      .try_borrow_mut()
-      .expect("required type is not present in GothamState container")
+    self.try_borrow_mut().unwrap_or_else(|| missing::<T>())
   }
 
   /// Tries to move a value out of the `GothamState` storage and return ownership.
@@ -77,12 +74,17 @@ impl GothamState {
   ///
   /// If a value of type `T` is not present in `GothamState`.
   pub fn take<T: 'static>(&mut self) -> T {
-    self
-      .try_take()
-      .expect("required type is not present in GothamState container")
+    self.try_take().unwrap_or_else(|| missing::<T>())
   }
 }
 
+fn missing<T: 'static>() -> ! {
+  panic!(
+    "required type {} is not present in GothamState container",
+    type_name::<T>()
+  );
+}
+
 #[cfg(test)]
 mod tests {
   use super::GothamState;
@@ -179,4 +181,13 @@ mod tests {
     assert!(state.try_take::<Alias1>().is_none());
     assert!(state.try_take::<Alias2>().is_none());
   }
+
+  #[test]
+  #[should_panic(
+    expected = "required type deno_core::gotham_state::tests::MyStruct is not present in GothamState container"
+  )]
+  fn missing() {
+    let state = GothamState::default();
+    let _ = state.borrow::<MyStruct>();
+  }
 }