Value with type money is 0 instead of empty string

[mmarkelov]

I got issue when pass falsy value to TextInput with money type:

<TextInputMask
           type="money"
           options={{
             precision: 0,
             separator: ' ',
             delimiter: ' ',
             unit: '',
             suffixUnit: '',
           }}
           value={null}
           placeholder="Test"
           onChangeText={() => {}}
         />

So here instead of placeholder I got 0.
Here is sand

I dive deep into code:

https://github.com/benhurott/react-native-masked-text/blob/0b04ce41087b5e97c5f13f114bdb513c6e107eb3/lib/masks/money.mask.js#L29

We will get 0 when we will pass empty string

So I think it should be some check for empty string before pass value to mask, maybe here:
https://github.com/benhurott/react-native-masked-text/blob/0b04ce41087b5e97c5f13f114bdb513c6e107eb3/lib/base-text-component.js#L76-L80

Something like this:

_getMaskedValue(value) {
       if (this._getDefaultValue(value) === '') {
           return ''
       }
        return this._maskHandler.getValue(
            this._getDefaultValue(value),
            this._getOptions());
    }

I can make PR, if it is right place to do this kind of check

[mmarkelov]

@benhurott thanks for quick fix!