Using gateway address (`{gwaddr}`) in `network` widget format strings breaks the widget

[ar-turek]

Putting {gwaddr} in any format string (for bar or tooltip) renders the entire format string unusable. When put in the bar the bar becomes empty, when put in the tooltip the tooltip doesn't render.

Waybar emits an error message when using {gwaddr}:

No other field behaves that way, only gwaddr.

I'm on Ubuntu 20.04, is there a way that's it not supported?