Fix: Address multiple issues with shell code in endpoint.sh

[ModeSevenIndustrialSolutions]

All of there were reported by the "shellcheck" linting tool. I'd suggest we add a pre-commit configuration file to the repository. I will raise a separate issue and PR for the necessary changes.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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