Port JS API to new Context API

lib/api/src/js/error.rs

@@ -1,4 +1,7 @@
 use crate::js::lib::std::string::String;
+use crate::js::trap::RuntimeError;
+#[cfg(feature = "std")]
+use std::borrow::Cow;
 #[cfg(feature = "std")]
 use thiserror::Error;
 
@@ -83,11 +86,27 @@ pub enum WasmError {
     #[cfg_attr(feature = "std", error("Unsupported feature: {0}"))]
     Unsupported(String),
 
+    /// A Javascript value could not be converted to the requested type.
+    #[cfg_attr(feature = "std", error("{0} doesn't match js value type {1}"))]
+    TypeMismatch(Cow<'static, str>, Cow<'static, str>),
+
     /// A generic error.
     #[cfg_attr(feature = "std", error("{0}"))]
     Generic(String),
 }
 
+impl From<wasm_bindgen::JsValue> for WasmError {
+    fn from(err: wasm_bindgen::JsValue) -> Self {
+        Self::Generic(
+            if err.is_string() && err.as_string().filter(|s| !s.is_empty()).is_some() {
+                err.as_string().unwrap_or_default()
+            } else {
+                format!("Unexpected Javascript error: {:?}", err)
+            },
+        )
+    }
+}
+
 /// The Serialize error can occur when serializing a
 /// compiled Module into a binary.
 /// Copied from wasmer_compiler::SerializeError
@@ -124,3 +143,45 @@ pub enum DeserializeError {
     #[cfg_attr(feature = "std", error(transparent))]
     Compiler(CompileError),
 }
+
+/// An error while instantiating a module.
+///
+/// This is not a common WebAssembly error, however
+/// we need to differentiate from a `LinkError` (an error
+/// that happens while linking, on instantiation), a
+/// Trap that occurs when calling the WebAssembly module
+/// start function, and an error when initializing the user's
+/// host environments.
+#[derive(Debug)]
+#[cfg_attr(feature = "std", derive(Error))]
+pub enum InstantiationError {
+    /// A linking ocurred during instantiation.
+    #[cfg_attr(feature = "std", error("Link error: {0}"))]
+    Link(String),
+
+    /// A runtime error occured while invoking the start function
+    #[cfg_attr(feature = "std", error(transparent))]
+    Start(RuntimeError),
+
+    /// Import from a different [`Context`].
+    /// This error occurs when an import from a different context is used.
+    #[cfg_attr(feature = "std", error("cannot mix imports from different contexts"))]
+    BadContext,
+
+    /// A generic error occured while invoking API functions
+    #[cfg_attr(feature = "std", error(transparent))]
+    Wasm(WasmError),
+}
+
+impl From<WasmError> for InstantiationError {
+    fn from(original: WasmError) -> Self {
+        Self::Wasm(original)
+    }
+}
+
+#[cfg(feature = "core")]
+impl std::fmt::Display for InstantiationError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "InstantiationError")
+    }
+}