got my go build working; added nil-safe check also

Signed-off-by: Brad Koehn <brad@koehn.com>

pkg/restic/exec_commands.go

@@ -153,6 +153,9 @@ func decodeBackupStatusLine(lastLine []byte) (backupStatusLine, error) {
 // have a newline at the end of it, so this returns the substring between the
 // last two newlines.
 func getLastLine(b []byte) []byte {
+	if b == nil {
+		return []byte("")
+	}
 	if len(b) == 0 {
 		return b
 	}

pkg/restic/exec_commands_test.go

@@ -81,6 +81,7 @@ third line
 			assert.Equal(t, []byte(tt.want), getLastLine([]byte(tt.output)))
 		})
 	}
+	assert.Equal(t, []byte(""), getLastLine(nil))
 }
 
 func Test_getVolumeSize(t *testing.T) {