where-vessels: complain if ocean or pirate are empty string

diff --git a/yarrg/where-vessels b/yarrg/where-vessels
index 9b8c7728a41ade97694f961749ba0d4b20ff3f64..272a11432b37f6c6d7169f773b89a621790e7326 100755 (executable)
--- a/yarrg/where-vessels
+++ b/yarrg/where-vessels
@@ -133,6 +133,9 @@ proc argdefaults {} {
        if {[info exists ocean]} { lappend cmd --ocean $ocean }
        if {[info exists pirate]} { lappend cmd --pirate $pirate }
        manyset [split [eval exec $cmd] " "] ocean pirate
+       if {![llength $ocean] || ![llength $pirate]} {
+           error "$ocean $pirate ?"
+       }
     }
     lappend scraper $ocean
 }