better error message for config issues

src/conf.rs

@@ -1,6 +1,6 @@
 use config::Config;
 use serde::{Serialize,Deserialize};
-use crate::errors::LJResult;
+use crate::errors::{LJError,LJResult};
 use crate::transformer;
 
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -46,7 +46,7 @@ impl Conf {
             .add_source(config::File::with_name(path))
 	    .build()?;
         
-	let conf : Conf = settings.try_deserialize()?;
+	let conf : Conf = settings.try_deserialize().map_err(LJError::Config)?;
 	Ok(conf)
     }
 

src/errors.rs

@@ -1,11 +1,13 @@
 use std::error::Error;
 use std::fmt;
 use redis::RedisError;
+use config::ConfigError;
 
 pub type LJResult<T> = Result<T, Box<dyn std::error::Error>>;
 
 #[derive(Debug)]
 pub enum LJError {
+    Config(ConfigError),
     RedisConnect(RedisError),
     HeliosDeviceMissing
 }
@@ -15,6 +17,10 @@ impl fmt::Display for LJError {
 	use LJError::*;
 	
 	match self {
+	    Config(err) => {
+		write!(f, "unable to load config file: {err}")
+	    },
+
 	    RedisConnect(err) => {
 		write!(f, "unable to connect to redis server: {err}")
 	    },