apply some pedantic lints

src/env.rs

@@ -7,7 +7,7 @@ pub(crate) fn get_editor() -> Result<String> {
 }
 
 fn check_vars_in_order(vars: &[&str]) -> Option<String> {
-    vars.iter().flat_map(|v| var(v).ok()).next()
+    vars.iter().find_map(|v| var(v).ok())
 }
 
 pub(crate) fn get_single_var(variable: &str) -> Option<String> {