runner._return_from_module() normally returns a list (?) of `[str,bool,dict,str]`, but on error it returns `[str,bool,str,str]`. runner._chain_file_module() then tries to call .get() on the third item (`data2`), which fails when it's a string. This patch only accesses `data2` if the return value was `ok`. It might be better to return consistent types in both cases, but I'm not sure where/how else the return value is used.
