Bug Report

Current Behavior
Given a array parameter with two trailing comments right after each other parsing the code fails with the error Cannot set property 'trailingComments' of null.

Input Code
https://astexplorer.net/#/gist/a9695795c5bcf8dcba3fd886b025add0/46534ba4d7c94712ba4d45ee0de058c0213ee0cf

function foo([foo, /* not used */, /* not used */]) {
}

Expected behavior/code
Babel parses the code without throwing Cannot set property 'trailingComments' of null

Environment

• Babel version(s): v7.6.0
• Node/npm version: Node 10/npm 6
• OS: Ubuntu 16.04
• Monorepo: no
• How you are using Babel: angular-cli

Additional context/Screenshots
Testing this locally I could reproduce the error using @babel/parser 7.6.2 and 7.6.0. Using @babel/parser 7.5.5 the above code parses just fine.
I suspect c0e3fa0#diff-0175b6ff28e6c7e30e7ecd5c13749187 might have introduced this.