Signal an error. Args are ERROR-SYMBOL and associated DATA.
This function does not return.
An error symbol is a symbol with an `error-conditions' property
that is a list of condition names.
A handler for any of those names will get to handle this signal.
The symbol `error' should normally be one of them.
DATA should be a list. Its elements are printed as part of the error message.
See Info anchor `(elisp)Definition of signal' for some details on how this
error message is constructed.
If the signal is handled, DATA is made available to the handler.
See also the function `condition-case'.
(fn ERROR-SYMBOL DATA)