notmuch: log any stderr output

notmuch/src/lib.rs

@@ -214,9 +214,8 @@ use std::{
     process::Command,
 };
 
-use log::{error, info};
 use serde::{Deserialize, Serialize};
-use tracing::instrument;
+use tracing::{error, info, instrument, warn};
 
 /// # Number of seconds since the Epoch
 pub type UnixTime = isize;
@@ -718,6 +717,13 @@ impl Notmuch {
         cmd.args(args);
         info!("{:?}", &cmd);
         let out = cmd.output()?;
+        if !out.stderr.is_empty() {
+            warn!(
+                "{:?}: STDERR:\n{}",
+                &cmd,
+                String::from_utf8_lossy(&out.stderr)
+            );
+        }
         Ok(out.stdout)
     }
 }