Fix infinite search loop bug

[vkbo]

Summary:

This issue fixes a case where a search triggers an infinite loop. It is caused by the QTextEdit returning True that a search was made, but does not select a text result. This causes an infinite loop in the search result counter. The loop will now break in such a case, and a cap has also been set on the number of search results to 1000. More results will in any case make the GUI sluggish on slower systems.

Related Issue(s):

Resolves #1015

Reviewer's Checklist:

• The header of all files contain a reference to the repository license
• The overall test coverage is increased or remains the same as before
• All tests are passing
• All flake8 checks are passing and the style guide is followed
• Documentation (as docstrings) is complete and understandable
• Only files that have been actively changed are committed