Error handling in Rust

1. Runtime error (panic) noticed during compilation.
2. Divide by zero panick in function
3. Return error on failure
4. Divide by zero runtime panic
5. Divide by zero return error
6. factorial function, runtime panic
7. factorial create panic
8. Out of bound for vectors
9. Out of bound for arrays
10. Open files
11. Error handling on the command line
12. main returning Result - Set exit code
13. Error in internal function