Crash: A malicious NFT can make app crash.

**Bug Description**
A malicious NFT can make alphawallet(adnroid) crash due to missing parameter validation . if an attacker send a Nft token to a alphawallet address, alphawallet will auto load the nft info in wallet .

step to reproduce:

1.deploy a NFT contract.

2.send a Nft token to any alphawallet user with a malicious tokenUri

3.user open the wallet app ,and click Nft item

4.app will crash.

or you can use this test mnemonic Phrase (ropsten)

`federal smile danger mixed palace equal intact wood goat digital patrol relax`

**Impact**
1.make app crash.

2.Let users have a lot of dirty data in their wallets .

you can view this video: https://www.ghostmaze.top/aw/nft_crash.mp4

tx:0xf1f1bf469d43279d4df81b9e66135054b327fae089122b2bde12b5060b7eb3eb (ropsten)

**Vulnerability Analysis**
`alpha-wallet-android-master\app\src\main\java\com\alphawallet\app\widget\NFTImageView.java`
loadImage funtion can load the Nft token metainfo from any website.

```
private void loadImage(String url, String backgroundColor, int corners) throws IllegalArgumentException
{
if (!Utils.stillAvailable(getContext())) return;

setWebViewHeight((int)getLayoutParams().width);

this.imageUrl = url;
fallbackLayout.setVisibility(View.GONE);
image.setVisibility(View.VISIBLE);
webLayout.setVisibility(View.GONE);

if (!TextUtils.isEmpty(backgroundColor))
{
int color = Color.parseColor("#" + backgroundColor);
ColorStateList sl = ColorStateList.valueOf(color);
holdingView.setBackgroundTintList(sl);
}
else
{
holdingView.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.transparent));
}

loadRequest = Glide.with(getContext())
.load(url)
.transform(new CenterCrop(), new RoundedCorners(corners))
.transition(withCrossFade())
.override(Target.SIZE_ORIGINAL)
.timeout(30 * 1000)
.listener(requestListener)
.into(new DrawableImageViewTarget(image)).getRequest();
}
```
when parse Nft BackgroundColor filed from metainfo, due to missing parameter validation , any malicious data can enter the function.

`int color = Color.parseColor("#" + backgroundColor);`
and in parseColor function , it will use parseLong() to parse backgroundColor parameter , if backgroundColor is not correct , it will crash . look like this:

`at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)`