replace the assert statements with throw statement

[NoureldinYosri]

when using Tesseract through the python interface, failed assert statements in the C++ layer cause the python session to crash ... throw statements are handled better by pybind11 and will show up as regular python exceptions https://github.com/quantumlib/tesseract-decoder/blob/main/.github/workflows/stable-release-workflow.yml

alternatively find out if pybind11 has a way to safely catch failed asserts