Command err handling (#480)

* ignore .vscode

* Improved error handling in command execution

- Modified function signatures to return errors
- Added error checks after command executions
- Added specific error messages for different failures
- Updated the handling of parser errors for source tape parsing
- Altered evaluator to incorporate the revised error handling

* Move waiting for "window.term" in VHS evaluator

- Moved the logic for waiting until the "window.term" variable is accessible from VHS setup to evaluation phase
- This ensures the proper timing and handling of errors related to the 'term' variable access (some SET commands access term)

* ignore unused param

.gitignore

@@ -8,3 +8,4 @@ completions
 dist
 vhs
 .idea/
+.vscode/