Write a Python program that takes a list of numbers as input from the user, calculates the sum of all even numbers in the list, and returns the result. The program should check if the input is valid (i.e., if it's a list of numbers), and if it's not, it should return an error message. The program should also handle exceptions gracefully and return a user-friendly error message in case of any exceptions.
length_constraints:number_sentences punctuation:no_comma detectable_content:number_placeholders language:response_language detectable_content:postscript change_case:capital_word_frequency startend:quotation
less than
ta
P.P.S
at least
Please make sure the response less than 3 sentences long In your response please avoid using commas The response must contain at least 2 placeholders represented by square brackets Please respond to me only in Tamil please explicitly add a note starting with P.P.S Use words in all capital letters at least 1 times You need to wrap your entire response in double quotes