FWIW, parsing and lexical analysis was the CS class I have used most thoroughly in my career. Sure data structures is probably the most often used, but other than hash tables and b-trees, not much of that class was useful. But lexing and parsing? Seems like every other project benefited by it either in handling configuration files, or log/sensor data, or some other need to convert what was human readable into machine manipulable.

That said, I really recommend the crafting interpreters work. It covers all the bases pretty solidly. If you want more depth and theory then get the dragon book (Ullman on compiler design) and read it afterwards :-)