Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/api/src/trap.rs

@@ -0,0 +1,22 @@
+use alloc::string::{String, ToString};
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+#[error("Wasm trap: {message}")]
+pub struct Trap {
+    message: String,
+}
+
+impl Trap {
+    pub fn new(message: String) -> Trap {
+        Trap { message }
+    }
+
+    pub fn fake() -> Trap {
+        Trap::new("TODO trap".to_string())
+    }
+
+    pub fn message(&self) -> &str {
+        &self.message
+    }
+}