query not possible on unnamed DataArray

[benHeid]

What happened:
The query operation crashes if I execute it on an unamed dataarray.

What you expected to happen:
The query operation is executed sucessfully

Minimal Complete Verifiable Example:

import xarray as xr
import numpy as np

da = xr.DataArray(np.arange(0, 5, 1), dims="x")
da.query(x="x > 1")

Anything else we need to know?:

Environment:

• Python 3.8
• Xarray 0.18.2
• OS: Windows

[TomNicholas]

Thanks for flagging this @benHeid , #5493 should fix it.