Demonstrate the unsuitable YAML syntax error when there is a space before "---" leading a vars/main.yml file

main.yml

 ---
# note the space before the ---
var1: "val"


# PRODUCES ERROR MESSAGE
# ansible-playbook -i hosts playbooks/test2.yml --limit=localhost
# [' var1', ' "val"']
# ERROR: Syntax Error while loading YAML script, /Users/kbroughton/vcp/git/21ct/proto/lynx-ansible/vars/main.yml
# Note: The error may actually appear before this position: line 3, column 6


# var1: "val"
#     ^
# We could be wrong, but this one looks like it might be an issue with 
# unbalanced quotes.  If starting a value with a quote, make sure the 
# line ends with the same set of quotes.  For instance this arbitrary 
# example:

#    foo: "bad" "wolf"

# Could be written as:

#    foo: '"bad" "wolf"'

playbook_demo.yml

---
 - hosts
   vars_files:
     - main.yml
   tasks:
   # call a variable in main.yml
   - debug: msg="{{var1}}"
  

assuming a suitable hosts file, running the following command reproduces the error.
$ ansible-playbook -i hosts playbook_demo.yml --limit=localhost