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_words startend:quotation keywords:frequency keywords:forbidden_words length_constraints:number_paragraphs detectable_format:number_highlighted_sections change_case:english_lowercase
at least
less than
relationships
health
Keep your entire response at least 13 words or less. Your answer need to be wrapped in double quotes Mention the word "relationships" for less than 2 times The words health cannot be in the response Please reply in details, and include exactly 3 paragraphs. Separate the paragraphs with *** Make sure to highlight at least 2 sections in your answer with markdown, i.e. use *highlighted section* All letters in your response must be lower case letters