Using Yield and return a list of error

I have a piece of code (an xls parser) that does some validation on the fields and returns with yield a generator that contains every row of the xls.

Now, i have to collect validation errors in a list, and use them when the generator is exhausted.

This is a piece of code that represent the parser and a poor designed solution.

error_list = []

def gen(limit): #xls parser
    for x in range(limit):
        if x%2: #fake error contition
            error_list.append(x)
        else:
            yield(x*x) #return

is there a more pythonic way to do this? i'm not a big fan of global variables.

i'd love to keep the code as it is as much as possible but if there's no other way i'll convert the function to a classic

def gen(limit): #xls parser
    error_list = []
    results = []
    for x in range(limit):
        if x%2: #fake error contition
            error_list.append(x)
        else:
            results.append(x*x)
    return results, error_list