add null check and move tag lookup to .contains() in global@custom

Signed-off-by: reyesj2 <[email protected]>

salt/elasticsearch/files/ingest/global@custom

@@ -15,8 +15,8 @@
     { "set":        { "if": "ctx.network?.direction == 'ingress'", "override": true, "field": "network.initiated", "value": "false" } },
     { "set":        { "if": "ctx.network?.type == 'ipv4'", "override": true, "field": "destination.ipv6", "value": "false" } },
     { "set":        { "if": "ctx.network?.type == 'ipv6'", "override": true, "field": "destination.ipv6", "value": "true" } },
-    { "set":        { "if": "ctx.tags.0 == 'import'", "override": true, "field": "data_stream.dataset", "value": "import" } },
-    { "set":        { "if": "ctx.tags.0 == 'import'", "override": true, "field": "data_stream.namespace", "value": "so" } },
+    { "set":        { "if": "ctx.tags != null && ctx.tags.contains('import')", "override": true, "field": "data_stream.dataset", "value": "import" } },
+    { "set":        { "if": "ctx.tags != null && ctx.tags.contains('import')", "override": true, "field": "data_stream.namespace", "value": "so" } },
     { "date":       { "if": "ctx.event?.module == 'system'", "field": "event.created", "target_field": "@timestamp","ignore_failure": true, "formats": ["yyyy-MM-dd'T'HH:mm:ss.SSSX","yyyy-MM-dd'T'HH:mm:ss.SSSSSS'Z'"] } },
     { "community_id":{ "if": "ctx.event?.dataset == 'endpoint.events.network'", "ignore_failure":true }  },
     { "set":        { "if": "ctx.event?.module == 'fim'", "override": true, "field": "event.module", "value": "file_integrity" } },