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