Validates that the input is a data.frame with exactly one column (series).
Intended for use in functions that operate on single tree-ring series.
Usage
check_single_series(x, arg_name = "x")
Arguments
- x
An object to check.
- arg_name
A string indicating the argument name (e.g., "x" or "y") for informative error messages.
Value
Invisibly returns TRUE if the input is valid; otherwise, throws an error.
