feat(core): include type name in state panic message (#13239)

* feat(core): include type name in state panic message

* tweak message

Author: lucasfernog

.changes/enhance-state-panic-message.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch:enhance
+---
+
+Enhance panic message when fetching unmanaged state.

crates/tauri/src/lib.rs

@@ -738,11 +738,12 @@ pub trait Manager<R: Runtime>: sealed::ManagerBase<R> {
   where
     T: Send + Sync + 'static,
   {
-    self
-      .manager()
-      .state
-      .try_get()
-      .expect("state() called before manage() for given type")
+    self.manager().state.try_get().unwrap_or_else(|| {
+      panic!(
+        "state() called before manage() for {}",
+        std::any::type_name::<T>()
+      )
+    })
   }
 
   /// Attempts to retrieve the managed state for the type `T`.

crates/tauri/src/state.rs

@@ -153,7 +153,7 @@ impl StateManager {
   pub fn get<T: Send + Sync + 'static>(&self) -> State<'_, T> {
     self
       .try_get()
-      .expect("state: get() when given type is not managed")
+      .unwrap_or_else(|| panic!("state not found for type {}", std::any::type_name::<T>()))
   }
 
   /// Gets the state associated with the specified type.
@@ -191,6 +191,13 @@ mod tests {
     }
   }
 
+  #[test]
+  #[should_panic(expected = "state not found for type core::option::Option<alloc::string::String>")]
+  fn get_panics() {
+    let state = StateManager::new();
+    state.get::<Option<String>>();
+  }
+
   #[test]
   fn simple_set_get() {
     let state = StateManager::new();