aws: check for existence of config file in aws_profiles

Fixes #7872

plugins/aws/aws.plugin.zsh

@@ -33,6 +33,7 @@ function aws_change_access_key {
 }
 
 function aws_profiles {
+  [[ -r "${AWS_CONFIG_FILE:-$HOME/.aws/config}" ]] || return 1
   reply=($(grep '\[profile' "${AWS_CONFIG_FILE:-$HOME/.aws/config}"|sed -e 's/.*profile \([a-zA-Z0-9_\.-]*\).*/\1/'))
 }
 compctl -K aws_profiles asp aws_change_access_key