Issue of .xml files in using Hyp3 data for Mintpy SBAS

[mengzeriolu]

Describe the bug
The use of smallbaselineApp on Hyp3-generated interferograms does not require .xml files. However, the presence of a .tif.xml file, which can be automatically generated by opening a .tif file with QGIS, confuses the smallbaselineApp and generates this bug:
File "...", line ..., in read_isce_xml for child in meta.findall("MDI"):
AttributeError: 'NoneType' object has no attribute 'findall'
The bug can only be fixed after all .tif.xml files are deleted.

To Reproduce
Steps to reproduce the behavior:
From the data folder open a unw_phase_clipped.tif with QGIS, and remove it from QGIS. This generates a .tif.xml file in the same folder. Run **!smallbaselineApp.py --dir {work_dir} {mintpy_config}_** will show you the error

Expected behavior
smallbaselineApp.py is disrupted. The task terminates. The bug can only be fixed after all .tif.xml files in the data folder system are deleted.

Additional context
I am using Jupyter Notebook, Python 3.9 or 3.10.

Full error message

PASTE ERROR MESSAGE HERE

System information

• Operating system:
• Python environment:
• MintPy version:
• InSAR processor/product:
• Your custom / default template file (if the bug is related to a specific dataset):

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