crash while access 'EEL'

### 🔍 Before submitting the issue

- [x] I have searched among the existing issues
- [x] I am using a Python virtual environment

### 🐞 Description of the bug

Crash while access 'EEL'
The file(shell.rst) can be open by ansys.

### 📝 Steps to reproduce

Test command:
$ python3.12 test.py
ENS
ENG
EEL
malloc(): invalid size (unsorted)
[1] 65346 abort python3.12 test.py

Test code: [test.py](https://gist.github.com/anlijun/c7baa661409b803549938efa6b979291)
Test file: [shell.rst](https://drive.google.com/file/d/1PpeG5fhwuy9UxEYk-Deyib82a7uT6SvF/view?usp=sharing)

### 💻 Which operating system are you using?

Linux

### 📀 Which ANSYS version are you using?

None

### 🐍 Which Python version are you using?

3.12

### 📦 Installed packages

```shell
ansys-mapdl-reader==0.55.1
appdirs==1.4.4
certifi==2025.8.3
charset-normalizer==3.4.2
colorama==0.4.6
contourpy==1.3.3
cpylog==1.6.0
cycler==0.12.1
docopt-ng==0.9.0
fonttools==4.59.0
idna==3.10
kiwisolver==1.4.8
matplotlib==3.10.5
numpy==1.26.4
packaging==25.0
pillow==11.3.0
platformdirs==4.3.8
pooch==1.8.2
pyNastran==1.4.1
pyparsing==3.2.3
PyQt5==5.15.11
PyQt5-Qt5==5.15.17
PyQt5_sip==12.17.0
python-dateutil==2.9.0.post0
pyvista==0.45.3
QtPy==2.4.3
requests==2.32.4
scipy==1.16.1
scooby==0.10.1
six==1.17.0
tqdm==4.67.1
typing_extensions==4.14.1
urllib3==2.5.0
vtk==9.4.2
```

Start by running python3.12 test.py with the linked test.py and shell.rst files, confirming the malloc crash when accessing EEL. Trace the reader path reached by that access and identify where the invalid memory state originates. Done means the same reproduction no longer aborts and the failing case is covered by a regression test.

Written by the indexing model from the issue text.