prevent a crash in ComposeActivity when ContentResolver raises a SecurityException

app/src/main/java/com/keylesspalace/tusky/ComposeActivity.java

@@ -37,7 +37,6 @@ import android.os.Bundle;
 import android.os.Environment;
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.preference.PreferenceManager;
 import android.provider.MediaStore;
 import android.support.annotation.AttrRes;
 import android.support.annotation.LayoutRes;
@@ -968,9 +967,14 @@ public final class ComposeActivity extends BaseActivity implements ComposeOption
             status.setUid(savedTootUid);
             tootDao.delete(status);
             for (QueuedMedia item : mediaQueued) {
+                try {
                     if (getContentResolver().delete(item.uri, null, null) == 0) {
                         Log.e(TAG, String.format("Did not delete file %s.", item.uri.toString()));
                     }
+                } catch (SecurityException e) {
+                    Log.e(TAG, String.format("Did not delete file %s.", item.uri.toString()), e);
+                }
+
             }
         }
         Snackbar bar = Snackbar.make(findViewById(R.id.activity_compose),