Provide proper default value to ui.range

[Mick235711]

Motivation

Currently, ui.range is completely unusable if you don't provide a value, despite its calling signature suggests that the value parameter is optional. For example, given the following code:

from nicegui import ui

ui.range(min=0, max=100)
ui.range(min=0, max=100, value={"min": 0, "max": 100})
ui.run()

Only one range slider will be shown, which seems to be confusing for beginners. Worse, there are no warnings/errors printed to the console, and the HTML is just blank for the first element.

Implementation

Provide a proper default value to the value parameter, initializing to the full range. Alternatively, we can also move value to be a required parameter (remove = None) to accurately reflect its nature.

Progress

• I chose a meaningful title that completes the sentence: "If applied, this PR will..."
• The implementation is complete.
• Pytests are added.
• Documentation has been added.

[evnchn]

Hello @Mick235711 thanks for the PR.

It's a fair fix. And retrospect we're actually kinda sloppy in terms of the types passed into Quasar across the library, passing Nones despite the intended type is str, for example. (NiceGUI wishlist, maybe?)

Generally fine for str but in the case of ui.range it broke things because it expects a dict.

@codingpaula As the initial author for ui.range, do read this in case I missed anything. Thanks!

[falkoschindler]

Thanks for the pull request, @Mick235711!
I wasn't aware that ui.range is broken if you only specify the required parameters min and max. Your PR seems to fix it perfectly.
Let's merge! 🚀