Extra semicolons are usually introduced by mistake, for example because:

• It was meant to be replaced by one more property declaration, but this was forgotten.
• There was a typo which lead the semicolon to be doubled, i.e. ;;.

See

• MISRA C:2004, 14.3 - Before preprocessing, a null statement shall only occur on a line by itself; it may be followed by a comment provided that the first character following the null statement is a white-space character.
• MISRA C++:2008, 6-2-3 - Before preprocessing, a null statement shall only occur on a line by itself; it may be followed by a comment, provided that the first character following the null statement is a white-space character.
• CERT, MSC12-C. - Detect and remove code that has no effect or is never executed
• CERT, MSC51-J. - Do not place a semicolon immediately following an if, for, or while condition
• CERT, EXP15-C. - Do not place a semicolon on the same line as an if, for, or while statement