The problem is that you have the reference from a USR wired into the leftmost property node. Since in the first run it has the default value, which has no meaning, it errors.
The solution would be either to move the code into the case structure or to use the First Run? VI (from the advanced palette) to take the value from the control the first time and the value from the SR in subsequent runs. Or to clear the error in the init case and so on.
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