Internal Error occurs when command block places sign

Make a dummy objective named "Money" and give yourself a value of, say, 500. Upon running the following command, the command block says "Internal error occurred trying to execute that command"... but it also works.

setblock ~ ~1 ~ minecraft:oak_sign[rotation=12]{Text1:"[\"Spawner\"]",Text2:"[{\"score\":{\"name\":\"@p\",\"objective\":\"Money\"}}]"}

You can see that the sign placed successfully behind the command block GUI in the image I've provided.