The problem is with what you've left off-screen: there is no input going into your mapping node. Here's how I fixed it:
Mapping nodes can be used for all sorts of vectors, so they don't make any assumptions about what should go into them if you don't specify. Texture nodes, on the other hand, try to take a best guess.
Additionally, notice that I specified a UV map for your tangent-space normal map node.
Finally, using mapping nodes with tiling normal maps in Blender is not ideal, because for whatever reason, no one has ever seen fit to provide a tangent input to the Normal Map node. Appropriate tangents should go through the same mapping process as the UV coords reading the normal map. For doing things like this, I would recommend using bump maps instead, which Blender handles more cleanly, or to create and edit an extra UV map instead of using a mapping node for the normal map. http://cpetry.github.io/NormalMap-Online/ is a free tool that does a reasonable job of converting normal maps to height (displacement, bump) maps.