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.

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• All automated tests pass
• Reference related Issues
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src/doc/Makefile

@@ -45,4 +45,4 @@ doc-help:
 	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
 
 apidoc:
-	@$(SPHINXAPIDOC) -o _apidoc $(PY_BASEDIR)
+	@$(SPHINXAPIDOC) -o _apidoc $(PY_BASEDIR) --separate