disk: Check for error objects returned by Getfsstat

disk/disk_darwin.go

@@ -23,7 +23,9 @@ func PartitionsWithContext(ctx context.Context, all bool) ([]PartitionStat, erro
 		return ret, err
 	}
 	fs := make([]Statfs, count)
-	_, err = Getfsstat(fs, MntWait)
+	if _, err = Getfsstat(fs, MntWait); err != nil {
+		return ret, err
+	}
 	for _, stat := range fs {
 		opts := "rw"
 		if stat.Flags&MntReadOnly != 0 {

disk/disk_freebsd.go

@@ -29,7 +29,9 @@ func PartitionsWithContext(ctx context.Context, all bool) ([]PartitionStat, erro
 	}
 
 	fs := make([]Statfs, count)
-	_, err = Getfsstat(fs, MNT_WAIT)
+	if _, err = Getfsstat(fs, MNT_WAIT); err != nil {
+		return ret, err
+	}
 
 	for _, stat := range fs {
 		opts := "rw"

disk/disk_openbsd.go

@@ -27,7 +27,9 @@ func PartitionsWithContext(ctx context.Context, all bool) ([]PartitionStat, erro
 	}
 
 	fs := make([]Statfs, count)
-	_, err = Getfsstat(fs, MNT_WAIT)
+	if _, err = Getfsstat(fs, MNT_WAIT); err != nil {
+		return ret, err
+	}
 
 	for _, stat := range fs {
 		opts := "rw"