UTF-8 BOM causes error

[thehappycheese]

Description

Opening a UTF-8 file containing a byte order mark (BOM) causes an error and the map viewer fails to load.

Reproduce

1. Try to open a UTF-8 .geojson file file starting with binary 0xFEFF (The UTF-8 Byte Order Mark or BOM).
2. A popup appears reading Renderer Failure: new ims export features.geojson. Unexpected token  in JSON at position 0 See screenshot below:

Also note in the above screenshot that Jupyter's text editor also incorrectly shows the BOM as a red dot. Opening the same .geojson file in VS Code works as expected; the the BOM is hidden.

Context

• Operating System and version: Windows 10
• Python Version: 3.9
• Browser and version: Chrome
• JupyterLab version: 3.0.16

The troublesome geojson file is the result of an export from an ESRI Web AppBuilder application.

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