I am also experiencing this issue and would be curious if anyone has found a solution.
Same problem, have you already solved it ?
I found this error was caused by my source path containing a directory with a dash, e.g. "src-shared". I renamed the directory without a dash ("srcShared") and no longer saw the error.
I had the same problem and fixed it removing a point (.) in a folder name.
Similar to jlidbeck´s fix.
Aparently you can´t use anything else but characters or numbers in paths / packages names / folders names.