What about the following changes:

1. remove the space in `: stat`
2. replace `err isNil ifTrue:ifFalse:` with `err ifNil:ifNotNil:`
3. name the first error message `'Warning: --base-path parameter ' , self basePath  , ' is not a directory.'`
4. name the second error message `'Warning: path at --base-path parameter ' , self basePath , ' does not exist.'`