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