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
Duplicate of MC-220024