I can reproduce. Now I will irresponsibly speculate about the problem for a moment 
I suspect this is happening because the Author field in the Strings to Document node is not equipped to deal with the thousands of words being input via the Content field from the preceding Tika Parser. It could have a more descriptive error message for sure, but in practical terms, I would never expect this to work.
EDIT: Alternatively, maybe the settings for the node should have checkboxes for the metadata off by default? This might help eliminate some confusion.