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 detectable_format:multiple_sections punctuation:no_comma startend:quotation length_constraints:nth_paragraph_first_word detectable_format:number_bullet_lists keywords:frequency
less than
SECTION
Stuart
less than
Stuart
The number of sentences in your response should be less than 3 Your response must contain 3 sections, mark the beginning of each section with SECTION X You are not allowed to use any commas in your response Please wrap your entire reply with double quotation marks answer exactly 4 paragraphs. Use 2 new lines to separate paragraphs. Start the first paragraph with the word "Stuart" Make sure the answer contains exactly 2 bullet points in markdown format reply should include the word "Stuart" less than 2 times