Include url in all Browse error conditions

This makes it safer to use fwd-browse as your BROWSER. Even if you haven't
started a fwd session at least you'll get the url the program you were using
wanted to open.

src/browse/browse_unix.rs

@@ -9,15 +9,23 @@ use users;
 use xdg;
 
 pub async fn browse_url_impl(url: &String) -> Result<()> {
-    let path = socket_path().context("Error getting socket path")?;
+    let path = socket_path().context(format!(
+        "fwd-browse: Error getting socket path. \n\
+         Start a fwd session to open: {url}"
+    ))?;
     let stream = UnixStream::connect(&path).await.context(
-        "Error connecting to socket (is fwd actually connected here?)",
+        format!(
+            "fwd-browse: Error connecting to socket (is fwd actually connected here?) \n\
+             Start a fwd session to open: {url}"),
     )?;
     let mut writer = MessageWriter::new(stream);
     writer
         .write(Message::Browse(url.clone()))
         .await
-        .context("Error sending browse message")?;
+        .context(format!(
+            "Error sending browse message \n\
+             Start a fwd session to open: {url}"
+        ))?;
     Ok(())
 }