feat(comp): Safety check for comp failure

Signed-off-by: Marc Khouzam <marc.khouzam@montreal.ca>

cmd/helm/completion.go

@@ -314,6 +314,11 @@ function __helm_get_completions
         __helm_debug "Populated completion cache with: $__helm_cache_completions"
     end
 
+    if test -z "$__helm_cache_completions"
+        __helm_debug "No completion, probably due to a failure"
+        return 0
+    end
+
     set -l directive (string sub --start 2 $__helm_cache_completions[-1])
     set -l comps $__helm_cache_completions[1..-2]