Bug - Modal, DropDownItem, TreeView - strict TypeScript type checking fails

[starpit]

Describe the problem
When strict: true type checking is enabled in TypeScript, three modules (at least) fail to compile. This seems to be due to a few uses of ... | null, e.g. in DropDownItem:

    tabIndex?: number | null; <-- removing the | null part makes typescript happy

why does patternfly have both the ? and the | null? this not only seems unnecessary duplication, but... doesn't type check.

Interface 'ModalProps' incorrectly extends interface 'HTMLProps<HTMLDivElement>'.
  Types of property ''aria-labelledby'' are incompatible.
    Type 'string | null | undefined' is not assignable to type 'string | undefined'.
      Type 'null' is not assignable to type 'string | undefined'.

Interface 'DropdownItemProps' incorrectly extends interface 'InternalDropdownItemProps'.
  Types of property 'tabIndex' are incompatible.
    Type 'number | null | undefined' is not assignable to type 'number | undefined'.
      Type 'null' is not assignable to type 'number | undefined'.

Interface 'TreeViewCheckProps' incorrectly extends interface 'Partial<InputHTMLAttributes<HTMLInputElement>>'.
  Types of property 'checked' are incompatible.
    Type 'boolean | null | undefined' is not assignable to type 'boolean | undefined'.
      Type 'null' is not assignable to type 'boolean | undefined'.

How do you reproduce the problem?
Enable strict type checking.

Expected behavior
Strict type checking is goodness, and should work.

Is this issue blocking you?
The workaround is not to use strict type checking...

Screenshots
n/a

What is your environment?

• OS: any
• Browser any
• Version @patternfly/react-core@4.221.3

What is your product and what release date are you targeting?

Any other information?

[nicolethoen]

This should be addressed as part of #6050

[starpit]

Interesting, thanks. I wouldn't have expected React strict mode to necessary give the same enforcement as TypeScript strict mode. Though perhaps in this case, it can.

[nicolethoen]

ah - i read this issue quickly - indeed it is different.
Thank you for reporting!