ImageTool hangs on opening some non-uniform data

[kmnhan]

Description

ImageTool hangs on opening data that includes a non-uniform coord with int64 dtype.

Expected behavior

Should behave the same way as float64

Minimal Complete Verifiable Example

import numpy as np
import xarray as xr
import erlab

xr.DataArray(
    np.random.rand(5, 5),
    coords=dict(
        x=np.arange(5, dtype=np.float64),
        y=np.array([1.0, 2.0, 6.0, 7.0, 9.0], dtype=np.int64),
    ),
).qshow()

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of erlab and its dependencies.

Additional context

No response