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.
language:response_language keywords:letter_frequency length_constraints:nth_paragraph_first_word startend:quotation detectable_content:number_placeholders detectable_format:number_bullet_lists change_case:capital_word_frequency
ko
less than
y
reduce
less than
Please respond to me only in Korean Contain less than 6 letter"y" in your response There should be exactly 4 paragraphs each separated by two new lines in your response. fourth paragraph must start with the word reduce Your answer need to be wrapped in double quotes make sure it contains at least 1 placeholders represented by square brackets, such as [name] Your answer must contain exactly 4 bullet point in Markdown using the following format:
* Bullet point one.
* Bullet point two.
... Use words in all capital letters less than 4 times