Move the document trait into a separate crate (#3035)

* add a default head method through eval
* remove the old document trait
* implement document for each platform
* pull out document into a dedicated crate to cut down on shared dependencies
---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/document/src/error.rs

@@ -0,0 +1,36 @@
+use std::error::Error;
+use std::fmt::Display;
+
+/// Represents an error when evaluating JavaScript
+#[derive(Debug)]
+#[non_exhaustive]
+pub enum EvalError {
+    /// The platform does not support evaluating JavaScript.
+    Unsupported,
+
+    /// The provided JavaScript has already been ran.
+    Finished,
+
+    /// The provided JavaScript is not valid and can't be ran.
+    InvalidJs(String),
+
+    /// Represents an error communicating between JavaScript and Rust.
+    Communication(String),
+
+    /// Represents an error serializing or deserializing the result of an eval
+    Serialization(serde_json::Error),
+}
+
+impl Display for EvalError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            EvalError::Unsupported => write!(f, "EvalError::Unsupported - eval is not supported on the current platform"),
+            EvalError::Finished => write!(f, "EvalError::Finished - eval has already ran"),
+            EvalError::InvalidJs(_) => write!(f, "EvalError::InvalidJs - the provided javascript is invalid"),
+            EvalError::Communication(_) => write!(f, "EvalError::Communication - there was an error trying to communicate with between javascript and rust"),
+            EvalError::Serialization(_) => write!(f, "EvalError::Serialization - there was an error trying to serialize or deserialize the result of an eval"),
+        }
+    }
+}
+
+impl Error for EvalError {}