Searches recursively and returns path of file in a given directory. Throws error
if multiple files with same name are found (in directory or sub-directory)
Parameters
dir: string
directory name
fileName: string
name of file to search in directory
Optional warnMsg: string
if file does not exist & warning message is passed,
then console log warning, and return. throws error otherwise
Searches recursively and returns path of file in a given directory. Throws error if multiple files with same name are found (in directory or sub-directory)