This fixes a crash with following error:
```
Traceback (most recent call last):
File "/usr/local/share/Cppcheck/addons/runaddon.py", line 8, in <module>
runpy.run_path(addon, run_name='__main__')
File "<frozen runpy>", line 291, in run_path
File "<frozen runpy>", line 98, in _run_module_code
File "<frozen runpy>", line 88, in _run_code
File "/usr/local/share/Cppcheck/addons/misra.py", line 4737, in <module>
main()
File "/usr/local/share/Cppcheck/addons/misra.py", line 4679, in main
checker.parseDump(item)
File "/usr/local/share/Cppcheck/addons/misra.py", line 4335, in parseDump
self.executeCheck(902, self.misra_9_2, cfg)
File "/usr/local/share/Cppcheck/addons/misra.py", line 4246, in executeCheck
check_function(*args)
File "/usr/local/share/Cppcheck/addons/misra.py", line 2104, in misra_9_2
misra_9.misra_9_x(self, data, 902)
File "/usr/local/share/Cppcheck/addons/misra_9.py", line 414, in misra_9_x
parser.parseInitializer(ed, eq.astOperand2)
File "/usr/local/share/Cppcheck/addons/misra_9.py", line 320, in parseInitializer
child = self.root.getChildByValueElement(self.ed)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'getChildByValueElement'
```
A minimal example and testcase is added.
The extra check for nextChild seems to fix it, however i did not read
the whole codebase, so maybe this creates other issues.
---------
Co-authored-by: Tim Blume <tbl@sevenstax-intern.de>