EDIT: Duplicate of MC-220024

Shaders that have a long multiline comment with many asterisks can cause the game to hang forever depending on how many asterisks are used.

Example:

/**************************************/

To Reproduce:

1. Download attached resource pack 'ShaderCommentBug.zip'

2. The multiline comment used is: 

/*****************************************************************/

3. Run game and use resource pack

4. The game should now hang seemingly forever