Neopixel errors are not clear

[jaustin]

Describe the bug
When a user hasn't first created a 'strip' object, the errors spawned by Neopixel blocks are unclear.

To Reproduce
Steps to reproduce the behavior:

1. Create a new project
2. Add the neopixel library
3. Drag one of the blocks that manipulates a 'strip' object into the program
4. See error

The error is "Program Error: r0 is null" which will not mean much to many people.

Expected behavior
The error the user gets should help them understand about the requirement for the object to be instatiated before it is used OR the blocks for manipulating the strip object are not available to the user until they've done the required instantiation (this seems harder/impossible to get right?)

[Lorrainbow]

The same bug I believe, if you set the brightness of a neopixel strip before you declare the strip you get a different error:

And when it downloads to the micro:bit it display a number error and creates an ASSERT file, attached.
ASSERT.TXT

[jaustin]

In MakeCode 2023, we still have

But the error on the block says:

I still think this is pretty confusing.