stage1/block_device_info: Improve failure logs for partitions without…

… filesystems

If the system contains an empty partition, one that has no filesystem
or for which blkid returns an empty output or error, let's log
that.

This can be reproduced by trying to provision with a balenaOS
flasher image which has no filesystem on /dev/sda5.

Change-type: patch
Signed-off-by: Alexandru Costache <[email protected]>

src/stage1/block_device_info/partition.rs

@@ -102,7 +102,11 @@ impl PartitionInfo {
         } else {
             Err(Error::with_context(
                 ErrorKind::InvParam,
-                &format!("Could not parse blkid output: '{}'", cmd_res),
+                &format!(
+                    "Empty or unexpected blkid output '{}' for path '{}'",
+                    cmd_res,
+                    &*device.as_ref().to_string_lossy()
+                ),
             ))
         }
     }