feat(tazjin/rlox): Synchronise parser state after errors

This lets the parser collect multiple errors instead of returning
after the first one, with some optimistic synchronisation after
encountering something that looks wonky.

Change-Id: Ie9d0ce8de9dcc7a3d1e7aa2abe15f74cab0ab96b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2236
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

users/tazjin/rlox/src/interpreter.rs

@@ -11,7 +11,7 @@ pub fn run(code: &str) {
             print_tokens(&tokens);
             match parser::parse(tokens) {
                 Ok(expr) => println!("Expression:\n{:?}", expr),
-                Err(error) => report_errors(vec![error]),
+                Err(errors) => report_errors(errors),
             }
         }
         Err(errors) => report_errors(errors),