Remove syn/error.rs; it was removed as a mod a while ago

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/syn/error.rs

@@ -1,11 +0,0 @@
-use thiserror::Error;
-
-#[derive(Error, Debug, Clone)]
-pub enum SyntaxError {
-    //#[error("unexpected {0}")]
-    //Unexpected(String),
-    #[error("expected {expected}, but got {got}")]
-    ExpectedGot { expected: String, got: String },
-}
-
-pub type Result<T, E = SyntaxError> = std::result::Result<T, E>;