fix(logs): remove config string from deserialization error log (#1872)

This commit removes the passed config string to mm2 while initializing from the error log if there was a deserialization error.

mm2src/mm2_main/src/mm2.rs

@@ -292,7 +292,10 @@ pub fn get_mm2config(first_arg: Option<&str>) -> Result<Json, String> {
 
     let mut conf: Json = match json::from_str(conf) {
         Ok(json) => json,
-        Err(err) => return ERR!("Couldn't parse.({}).{}", conf, err),
+        // Syntax or io errors may include the conf string in the error message so we don't want to take risks and show these errors internals in the log.
+        // If new variants are added to the Error enum, there can be a risk of exposing the conf string in the error message when updating serde_json so
+        // I think it's better to not include the serde_json::error::Error at all in the returned error message rather than selectively excluding certain variants.
+        Err(_) => return ERR!("Couldn't parse mm2 config to JSON format!"),
     };
 
     if conf["coins"].is_null() {