Fix export when collecting browsers/systems is disabled

Would end up as NULL.

Aside: these columns pronably should be NULL in hits; no reason to store
it as "0". Same with location column.

.github/workflows/test.yml

@@ -1,9 +1,5 @@
 name: 'test backend'
-on:
-  push:
-    paths: ['**.go', 'go.mod', '.github/workflows/*']
-  pull_request:
-    paths: ['**.go', 'go.mod', '.github/workflows/*']
+on:   ['push', 'pull_request']
 
 jobs:
   # Uncomment to get a debug shell.

export.go

@@ -442,15 +442,15 @@ func (h *ExportRows) Export(ctx context.Context, limit, paginate int64) (int64,
 			paths.title,
 			paths.event,
 
-			browsers.name || ' ' || browsers.version as browser,
-			systems.name  || ' ' || systems.version  as system,
+			coalesce(browsers.name || ' ' || browsers.version, '') as browser,
+			coalesce(systems.name  || ' ' || systems.version, '')  as system,
 
 			hits.session,
 			hits.bot,
 			coalesce(refs.ref, '')        as ref,
 			coalesce(refs.ref_scheme, '') as ref_s,
 			coalesce(sizes.size, '')      as size,
-			hits.location                 as loc,
+			coalesce(hits.location, '')   as loc,
 			hits.first_visit              as first,
 			hits.created_at
 		from hits

go.mod

@@ -26,15 +26,15 @@ require (
 	zgo.at/errors v1.3.0
 	zgo.at/follow v0.0.0-20240522232612-673fb184d32f
 	zgo.at/gadget v1.0.0
-	zgo.at/guru v1.1.0
+	zgo.at/guru v1.2.0
 	zgo.at/isbot v1.0.0
 	zgo.at/json v0.0.0-20221020004326-fe4f75bb278e
 	zgo.at/termtext v1.5.0
 	zgo.at/tz v0.0.0-20240819050900-3c7bf6122612
 	zgo.at/z18n v0.0.0-20240522230155-4d5af439f8c4
 	zgo.at/zcache v1.2.0
 	zgo.at/zcache/v2 v2.1.0
-	zgo.at/zdb v0.0.0-20240818155550-1a862f98cab0
+	zgo.at/zdb v0.0.0-20240820041039-abefdffc704f
 	zgo.at/zhttp v0.0.0-20240819012318-b761c83c740e
 	zgo.at/zli v0.0.0-20240614180544-47534b1ce136
 	zgo.at/zlog v0.0.0-20211017235224-dd4772ddf860