Application Crashing on entering wrong pull request number #93

Description:

Application is crashing when entering wrong pull request number to view the Pull request Details modal. If a user is entering wrong pull request number or invalid pull request in the /github Username/RepositoryName pulls pullNumber command then the Rocket.Chat server is crashing.

Steps to reproduce:

1. Enter the command /github Username/RepositoryName pulls pullNumber with some wrong PR number.
2. Notice application is crashing

Expected behavior:

A invalid-message modal should open in case of any wrong input.

Additional context