bit better error handling

src/usimp/mod.rs

@@ -7,7 +7,7 @@ use crate::error::*;
 pub fn endpoint(endpoint: &str, input: serde_json::Value) -> Result<serde_json::Value, Error> {
     match endpoint {
         "echo" => Ok(serde_json::to_value(echo(serde_json::from_value(input)?))?),
-        _ => Err(Error::new(ErrorKind::InvalidEndpoint)),
+        _ => Err(Error::new(ErrorKind::InvalidEndpointError)),
     }
 }