DOC: Update tutorial on error handling

Summary

The error handling has been updated in the tutorial (see #52 (closed)). Also, #49 (closed) has been fixed on the way.

Focus

src/doc/tutorials/erros.rst

Test Environment

make doc on top level and look at build/doc/html/tutorials/errors.html.

Check List for the Author

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• All automated tests pass
• Reference related Issues
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  • Intent of new code
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Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
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README_SETUP.md

@@ -138,7 +138,7 @@ Out[2]: Connection to CaosDB with 501 Records.
 Note: This setup will ask you for your password whenever a new connection is created. If you do not
 like this, check out the "Authentication" section in the [configuration documentation](configuration.md).
 
-Now would be a good time to continue with the [tutorials](tutorials.html).
+Now would be a good time to continue with the [tutorials](tutorials/index.html).
 
 ## Run Unit Tests
 tox