When a user passes an empty string or whitespace-only string as an argument, the tool should reject it with a clear error message instead of silently proceeding or crashing.
Acceptance Criteria
- Passing
"" or " " as input prints a user-friendly error: Error: input must not be empty
- Exit code is non-zero (e.g. 1)
- Unit test added covering both empty and whitespace-only cases
When a user passes an empty string or whitespace-only string as an argument, the tool should reject it with a clear error message instead of silently proceeding or crashing.
Acceptance Criteria
""or" "as input prints a user-friendly error:Error: input must not be empty