NullPointerException in HttpSender.java for USER_COMMENT field

[betfix]

I use ACRA version 4.9.2. But when the app crashes, no reports are sent to the backend and instead I can see the following in the logcat:

...
D/ACRA: Connect to http://192.168.0.12/acra-backend/report.php
E/ACRA: Failed to send crash reports for /data/data/com.my.app/app_ACRA-approved/2017-06-13T07:46:49.808+0000-IS_SILENT.stacktrace 
java.lang.NullPointerException
    at org.acra.sender.HttpSender.remap(HttpSender.java:254)
...

During debugging I discovered that in line 254 in HttpSender.java (https://github.com/ACRA/acra/blob/acra-4.9.2/src/main/java/org/acra/sender/HttpSender.java) when field is equal to "USER_COMMENT" then report.get(field) is NULL, and this causes the null pointer exception with flatten() function. It's the only NULL field of all 28 fields. By the way, the IS_SILENT field is false (but maybe that's ok)

So in order to really send the report I made a local copy and changed this line in HttpSender.java:

String value = TextUtils.join("\n", report.get(field).flatten());

into this code:

Element element = report.get(field);
String[] flattened;
if (element != null) {
    flattened = element.flatten();
} else {
    flattened = new String[0];
}
String value = TextUtils.join("\n", flattened);

It looks like an error in ACRA, but then it would be for everyone and not only for me. Perhaps I messed some configuration? How to deal with it without hacking?

P.S.

My Application config is as follows:

@ReportsCrashes(
    formUri = "http://192.168.0.12/acra-backend/report.php"
)
public class MyApplication extends Application {
    @Override
    protected void attachBaseContext(Context base) {
        super.attachBaseContext(base);
        ACRA.DEV_LOGGING = true;
        ACRA.init(this);

    }
}

[F43nd1r]

Duplicate of #541