Automatically create a list of cdms2 errors in global_time_series

[forsyth2]

Currently, errors in ts.globalAnnual(var) (https://github.com/E3SM-Project/zppy/blob/main/zppy/templates/coupled_global.py#L192) will raise CDMSError("No such variable, " + id) cdms2.error.CDMSError: No such variable. If the variable is added to the glb ts task, the error goes away, but may be replaced by the same error with a new variable.

By catching the exceptions in the loop and creating a list of exceptions, we could catch all of these at once.

[forsyth2]

Something like the following, replacing Exception with CDMSError, and printing var rather than v.

    exceptions = []
    for var in vars:
        print(var)
        try:
            v = ts.globalAnnual(var)
            exp["annual"][var] = v
            if "year" not in exp["annual"]:
                time = v.getTime()
                exp["annual"]["year"] = [x.year for x in time.asComponentTime()]
        except Exception:
            exceptions.append(v)
    if exceptions:
        raise Exception(exceptions)

[forsyth2]

Would also need to apply similar logic to the derivations in readTS.py