Fixed counting null message IDs

app/src/main/java/eu/faircode/email/DaoMessage.java

@@ -55,7 +55,7 @@ public interface DaoMessage {
             ", " + unflagged_unified + " AS unflagged" +
             ", (SELECT COUNT(a.id) FROM attachment a WHERE a.message = message.id) AS attachments" +
             ", SUM(CASE WHEN folder.type = '" + EntityFolder.DRAFTS + "' THEN 1 ELSE 0 END) AS drafts" +
-            ", COUNT(DISTINCT message.msgid) AS visible" +
+            ", COUNT(DISTINCT CASE WHEN message.msgid IS NULL THEN '' ELSE message.msgid END) AS visible" +
             ", MAX(CASE WHEN :found OR folder.unified THEN message.received ELSE 0 END) AS dummy" +
             " FROM message" +
             " JOIN account ON account.id = message.account" +
@@ -95,7 +95,7 @@ public interface DaoMessage {
             ", " + unflagged_folder + " AS unflagged" +
             ", (SELECT COUNT(a.id) FROM attachment a WHERE a.message = message.id) AS attachments" +
             ", SUM(CASE WHEN folder.type = '" + EntityFolder.DRAFTS + "' THEN 1 ELSE 0 END) AS drafts" +
-            ", COUNT(DISTINCT message.msgid) AS visible" +
+            ", COUNT(DISTINCT CASE WHEN message.msgid IS NULL THEN '' ELSE message.msgid END) AS visible" +
             ", MAX(CASE WHEN folder.id = :folder THEN message.received ELSE 0 END) AS dummy" +
             " FROM message" +
             " JOIN account ON account.id = message.account" +