fix: set initial progress to 0

[kontrollanten]

For convenient usage, set initial progress to 0 to let the consumer to skip to check if progress isn't NaN.

[kukhariev]

progress = 0

[Chocobozzz]

offset should also be initialized to not have NaN in uploading state

[kukhariev]

@Chocobozzz
I'm not sure to understand: offset: number | undefined is internal, not a member of UploadState.

ngx-uploadx/src/uploadx/lib/uploadx.service.ts

Lines 18 to 31 in 5d946e5

	export const UPLOAD_STATE_KEYS: (keyof UploadState)[] = [
	'file',
	'name',
	'progress',
	'remaining',
	'response',
	'responseHeaders',
	'responseStatus',
	'size',
	'speed',
	'status',
	'uploadId',
	'url'
	];

[Chocobozzz]

@kukhariev It's used to calculate progress: https://github.com/kukhariev/ngx-uploadx/blob/master/src/uploadx/lib/uploader.ts#L280

And undefined + 30 = NaN so we still have a NaN for the first progress state

[kukhariev]

Thanks!, should be fixed by #374