Make compile error failable

Author: morr0ne

src/error.rs

@@ -1,6 +1,8 @@
 use lalrpop_util::ParseError;
 use std::fmt;
 use unicode_width::UnicodeWidthStr;
+#[cfg(feature = "wasm")]
+use wasm_bindgen::JsValue;
 
 #[derive(Debug)]
 pub struct Error {
@@ -39,6 +41,13 @@ impl fmt::Display for Error {
 
 impl std::error::Error for Error {}
 
+#[cfg(feature = "wasm")]
+impl Into<JsValue> for Error {
+    fn into(self) -> JsValue {
+        JsValue::null() // FIXME: somehow convert the error
+    }
+}
+
 impl Error {
     fn new(file_name: &str, message: String, source: &str, pos: usize) -> Self {
         let mut line = 1;

src/lib.rs

@@ -129,19 +129,18 @@ const JS_PRELUDE: &str = include_str!("prelude.js");
 
 #[cfg(feature = "js")]
 #[cfg_attr(feature = "wasm", wasm_bindgen)]
-pub fn compile_to_js(source: &str) -> String {
+pub fn compile_to_js(source: &str) -> Result<String, crate::error::Error> {
     let parser = ProgramParser::new();
 
     let program = parser
         .parse(&source)
-        .map_err(|error| Error::from_parse_error("unknown", &source, error))
-        .expect("Failed");
+        .map_err(|error| Error::from_parse_error("unknown", &source, error))?;
 
     let allocator = Allocator::default();
 
     let converter = AstConverter::new(AstBuilder::new(&allocator));
     let program = converter.convert(program);
     let js = Codegen::new().build(&program);
 
-    format!("{JS_PRELUDE}{}", js.code)
+    Ok(format!("{JS_PRELUDE}{}", js.code))
 }

src/main.rs

@@ -27,11 +27,11 @@ fn main() -> Result<()> {
 
             path.set_extension("js");
 
-            fs::write(&path, compile_to_js(&source))?;
+            fs::write(&path, compile_to_js(&source)?)?;
         }
         Commands::Run { path } => {
             let source = fs::read_to_string(&path)?;
-            let source = compile_to_js(&source);
+            let source = compile_to_js(&source)?;
 
             Command::new("deno")
                 .arg("eval")