Add common errors

Author: ColinWttt

astro.config.mjs

@@ -34,7 +34,7 @@ export default defineConfig({
         },
         {
           label: "Common Errors",
-          items: ["errors/errors"],
+          autogenerate: { directory: 'errors' },
         },
       ],
     }),

src/content/docs/errors/bind_mut_fail.md

@@ -0,0 +1,27 @@
+---
+title: Gd<T>::bind_mut() failed, already bound
+description: Gd<T>::bind_mut() failed, already bound
+---
+
+## Reason
+This error typically occurs when you attempt to get a mutable borrow (`bind_mut()`) of a Godot object that is already borrowed (either immutably or mutably). A common scenario is calling `self.to_gd().bind_mut()`.
+
+## Solutions
+
+Choose one of the following solutions:
+
+1. **(Recommended)** Avoid `self.to_gd().bind_mut()`. Instead, use `self.base_mut().some_base_method()` to call methods on the base class mutably.
+
+2. **Change Function Signature:** If you are passing the object to another function, consider passing a mutable reference to your _struct type_ (`&mut MyClass`) instead of `Gd<MyClass>`, if feasible. This allows direct field access in the receiving function without needing `bind_mut`.
+
+3. **Use `base_mut()` Guard Carefully:** 
+
+```rust
+fn custom_method(&mut self) { 
+    let gd = self.to_gd(); 
+    // guard
+    let _guard = self.base_mut(); 
+    // now it's safe to call bind
+    gd.bind()
+}
+```

src/content/docs/errors/cannot_find_signal.md

@@ -0,0 +1,17 @@
+---
+title: Cannot find attribute `signal` in this scope
+description: Cannot find attribute `signal` in this scope
+---
+
+## Solutions:
+
+1. Declare the `signal` in the class impl block.
+2. Add `#[godot_api]` on the impl block that contains the signal.
+
+```rust
+#[godot_api]
+impl MyClass {
+    #[signal]
+    fn custom_signal();
+}
+```

src/content/docs/errors/errors.md

@@ -0,0 +1,20 @@
+---
+title: The trait bound `...ToGodot` is not satisfied
+description: The trait bound `YourClass:godot::prelude::ToGodot` is not satisfied.
+---
+
+## Error
+
+The trait bound `YourClass:godot::prelude::ToGodot` is not satisfied.
+
+## Reason
+
+you need to define how to pass it around in godot(e.g. `function with #[func]`).  
+Otherwise godot have no idea how to reference your Class in functions that talk about it.
+
+## Solutions
+
+Choose one of the following solutions:
+
+1. (Recommend) Change `YourClass` to `Gd<YourClass>`.
+2. Implementing `GodotConvert`, `ToGodot`, and `FromGodot` to use some other type as an intermediate.