Bug: App accepts 0 as a Weight value

[isacostaf]

Bug description: The program allows the user to input 0 as a Weight value

Expected behavior: The program should only validate the weight if it's not null or 0. Also, in my opinion, the program should have a limit for weight inputs, since not having one can contribute to eating disorders.

Environment: Web (Chrome)

Possible solution: Add validation to check if the weight is different then 0.

[JEdits20]

#218 implements the weight input validation