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.
detectable_format:multiple_sections detectable_content:number_placeholders keywords:existence change_case:capital_word_frequency keywords:letter_frequency keywords:forbidden_words length_constraints:nth_paragraph_first_word
Section
heart
less than
less than
e
falling
falling
Make sure to include at least 3 sections marking the beginning of each section with 'Section X' make sure it contains at least 1 placeholders represented by square brackets, such as [name] The response must include the keywords heart Respond with less than 4 words be in all capital letters The letter e should show up less than 5 times Do not include the keywords: falling Write exactly 2 paragraphs each separated with two new lines answering this instruction. The first paragraph must start with "falling"