getInputRef type mismatch with using TextField material-ui.

[IgnorantCoder]

Hello.
I am using this module with material-ui.

I got the compile error in using it in TypeScript.
I found out type mismatch between getInputRef and inputRef that passed from material-ui.
I want to make type restriction of getInputRef lax for solving this problem.

Problem:

        <NumberFormat
            getInputRef={inputRef} 
            value={value as number}
            onValueChange={(values) => {
                if (onChange === undefined) {
                    return;
                }

                const event = {
                    target: {
                        value: values.value,
                    },
                } as React.ChangeEvent<HTMLInputElement>;
                onChange(event);
            }}
        />

error:

TS2326: Types of property 'getInputRef' are incompatible.
  Type 'string | ((instance: any) => any) | RefObject<any> | undefined' is not assignable to type '((el: HTMLInputElement) => void) | undefined'.
  Type 'string' is not assignable to type '((el: HTMLInputElement) => void) | undefined'.

Workarround:

        <NumberFormat
            getInputRef={inputRef as (el: HTMLInputElement) => void}
            value={value as number}
            onValueChange={(values) => {
                if (onChange === undefined) {
                    return;
                }

                const event = {
                    target: {
                        value: values.value,
                    },
                } as React.ChangeEvent<HTMLInputElement>;
                onChange(event);
            }}
        />