Add error handling

Signed-off-by: Harald Albers <github@albersweb.de>

Author: albers

cli/command/system/completion.go

@@ -52,14 +52,16 @@ var (
 "untag",
 "update",
 }
+eventTypes = []string{"config", "container", "daemon", "image", "network", "node", "plugin", "secret", "service", "volume"}
 )
-var eventTypes = []string{"config", "container", "daemon", "image", "network", "node", "plugin", "secret", "service", "volume"}
 
 func completeFilters(dockerCLI completion.APIClientProvider) completion.ValidArgsFn {
 return func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 if strings.HasPrefix(toComplete, "container=") {
-// the pure container name list should be pulled out from ContainerNames.
 names, _ := completion.ContainerNames(dockerCLI, true)(cmd, args, toComplete)
+if names == nil {
+return nil, cobra.ShellCompDirectiveNoFileComp
+}
 return prefixWith("container=", names), cobra.ShellCompDirectiveDefault
 }
 if strings.HasPrefix(toComplete, "event=") {
@@ -69,8 +71,10 @@ func completeFilters(dockerCLI completion.APIClientProvider) completion.ValidArg
 return nil, cobra.ShellCompDirectiveNoFileComp
 }
 if strings.HasPrefix(toComplete, "network=") {
-// the pure network name list should be pulled out from NetworkNames.
 names, _ := completion.NetworkNames(dockerCLI)(cmd, args, toComplete)
+if names == nil {
+return nil, cobra.ShellCompDirectiveNoFileComp
+}
 return prefixWith("network=", names), cobra.ShellCompDirectiveDefault
 }
 if strings.HasPrefix(toComplete, "type=") {