Number 0 is omitted when converting object to xml

[linkeo]

Describe the bug
When converting object to xml, it's not expected to convert number 0 into empty content.

To Reproduce

const { create } = require('xmlbuilder2');

const xml = create().ele({ value: 0 }).end()

will produce

<?xml version="1.0"?><root><value/></root>

Expected behavior

It should be

<?xml version="1.0"?><root><value>0</value></root>

Version:

• node.js: [12.13.0]
• xmlbuilder2 [2.1.2]

Additional context
Add any other context about the problem here.

[linkeo]

@oozcitak Is it ok to change this condtion to else if (value != null)

xmlbuilder2/src/builder/XMLBuilderImpl.ts

Lines 170 to 172 in 3a30fbe

	lastChild.ele(val)
	} else if (val) {
	// leaf element node with a single text node

[oozcitak]

Yes that should do it. Would you like to send a PR?

[linkeo]

@oozcitak ok, i will send it soon