Add no-param-reassign from eslint (#3089)

While waiting for the easterbunny I cleaned up some bad coding practice
:-)

Very open for comments especially regarding the places I commented
myself...

---------

Co-authored-by: veeck <michael@veeck.de>

.eslintrc.json

@@ -24,6 +24,7 @@
 	"rules": {
 		"eqeqeq": "error",
 		"import/order": "error",
+		"no-param-reassign": "error",
 		"no-prototype-builtins": "off",
 		"no-throw-literal": "error",
 		"no-unused-vars": "off",