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.
punctuation:no_comma change_case:capital_word_frequency length_constraints:nth_paragraph_first_word language:response_language detectable_content:number_placeholders detectable_format:number_bullet_lists detectable_content:postscript
less than
HARSH
te
P.S.
In your response please avoid using commas Add stress words which are capitalized. Limit those stress words for less than 4 times Write exactly 4 paragraphs each separated with two new lines answering this instruction. The fourth paragraph must start with "HARSH" response should be entirely in Telugu, no other language is allowed Your answer must also contain at least 1 placeholder (an example of a placeholder is [address]) Include exactly 3 bullet points in your response. The bullet points should be in the form of:
* This is bullet 1
* This is bullet 2
...
 At the end of your response, please explicitly add a postscript starting with P.S.