Mishandled expected error

Description

A user recently reported that he didn't like the way dblab handles error happening at getting the metadata of a table. The way it works right now is that dblab crashes and prints out the error. The expected behavior is that every error generated by queries are printed on the rows view. So, I went ahead and made sure those errors are printed on the view mentioned above.

Fixes #227

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Unfortunately, the gui package doesn't have a test suite. To test this out, I hard-coded a non-existent table. This is supposed to error out due to the table is no present in the database.

Now, the expected error shows up on the rows table.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have checked my code and corrected any misspellings