fix crash in ComposeActivity when account has no profile picture set

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

@@ -456,11 +456,15 @@ public final class ComposeActivity extends BaseActivity
 
             ImageView composeAvatar = findViewById(R.id.composeAvatar);
 
+            if(TextUtils.isEmpty(activeAccount.getProfilePictureUrl())) {
+                composeAvatar.setImageResource(R.drawable.avatar_default);
+            } else {
                 Picasso.with(this).load(activeAccount.getProfilePictureUrl())
                         .transform(new RoundedTransformation(7, 0))
                         .error(R.drawable.avatar_default)
                         .placeholder(R.drawable.avatar_default)
                         .into(composeAvatar);
+            }
 
             composeAvatar.setContentDescription(
                     getString(R.string.compose_active_account_description,