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