unclear errors when config yaml file is badly formatted

[ctb]

checking for required files:
--------

while parsing a block mapping
  in "examples/yeast.yaml", line 36, column 3
expected <block end>, but found '<block mapping start>'
  in "examples/yeast.yaml", line 37, column 5
Traceback (most recent call last):
  File "./run_eelpond", line 351, in <module>
    sys.exit(main(args))
  File "./run_eelpond", line 186, in main
    configD = import_configfile(configfile)
  File "/mnt/research/ged/ctb/eelpond/ep_utils/utils.py", line 45, in import_configfile
    configDict = read_yaml(config_file)
  File "/mnt/research/ged/ctb/eelpond/ep_utils/utils.py", line 37, in read_yaml
    return yamlD
UnboundLocalError: local variable 'yamlD' referenced before assignment```

[ctb]

desired behavior: "your config yaml file is messed up, yo. here's the likely problem: "