Fix parseUri null pointer crash on Android

[AndrewJack]

I've seen this error occur frequently on rebel Android devices. Such as Xperia Z3, Galaxy S4 Mini, HUAWEI P9.

Fatal Exception: java.lang.RuntimeException: Error receiving broadcast Intent { act=android.intent.action.DOWNLOAD_COMPLETE flg=0x10 pkg=com.example (has extras) } in com.RNFetchBlob.f@ca10249
       at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:895)
       at android.os.Handler.handleCallback(Handler.java:739)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at android.os.Looper.loop(Looper.java:234)
       at android.app.ActivityThread.main(ActivityThread.java:5526)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by java.lang.NullPointerException: uriString
       at android.net.Uri$StringUri.(Uri.java)
       at android.net.Uri$StringUri.(Uri.java)
       at android.net.Uri.parse(Uri.java:442)
       at com.RNFetchBlob.RNFetchBlobReq.onReceive(RNFetchBlobReq.java:637)
       at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:885)
       at android.os.Handler.handleCallback(Handler.java:739)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at android.os.Looper.loop(Looper.java:234)
       at android.app.ActivityThread.main(ActivityThread.java:5526)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)