Option "Fixed contour interval" crashes in QGIS 3

Steps to reproduce:

Add delimited text in QGIS
Open Contour plugin
The delimited-text layer is selected as input, now pick the Data value ("field_3" in my case)
(the plugin calculates the predefined values)
In "contouring" switch to "Fixed contour interval"

The plugin crashes immediately after. When the error message is dismissed, the running of both QGIS and Contour plugin continues seamlessly.

System info: Contour plugin 2.0.1 QGIS 3.0.3 Windows 10 (v. 1803)

The error message:

NameError: name 'self' is not defined 
Traceback (most recent call last):
  File "C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour\ContourDialog.py", line 506, in computeLevels
    self.showLevels()
  File "C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour\ContourDialog.py", line 512, in showLevels
    levels=self._generator.levels()
  File "C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour\ContourGenerator.py", line 366, in levels
    self._levels=ContourMethod.calculateLevels(z,method,**params)
  File "C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour\ContourMethod.py", line 204, in calculateLevels
    return m.calc(z,**params)
  File "C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour\ContourMethod.py", line 100, in 
    func=lambda z,**kwa: _methodFunc(z,f,name,req,opt,kwa)
  File "C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour\ContourMethod.py", line 80, in _methodFunc
    return _sortedLevels(f(z,*pav,**kwv))
  File "C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour\ContourMethod.py", line 186, in calcIntervalContours
    .format(nmax-nmin,self.MaxContours))
NameError: name 'self' is not defined

Verze Pythonu: 3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 08:06:12) [MSC v.1900 64 bit (AMD64)] 
QGIS verze: 3.0.3-Girona Girona, 8a899c8758 

Python cesta:
C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\contour
C:/PROGRA~1/QGIS3~1.0/apps/qgis/./python
C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python
C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins
C:/PROGRA~1/QGIS3~1.0/apps/qgis/./python/plugins
C:\PROGRA~1\QGIS3~1.0\bin\python36.zip
C:\PROGRA~1\QGIS3~1.0\apps\Python36\DLLs
C:\PROGRA~1\QGIS3~1.0\apps\Python36\lib
C:\PROGRA~1\QGIS3~1.0\bin
C:\PROGRA~1\QGIS3~1.0\apps\Python36
C:\PROGRA~1\QGIS3~1.0\apps\Python36\lib\site-packages
C:\PROGRA~1\QGIS3~1.0\apps\Python36\lib\site-packages\win32
C:\PROGRA~1\QGIS3~1.0\apps\Python36\lib\site-packages\win32\lib
C:\PROGRA~1\QGIS3~1.0\apps\Python36\lib\site-packages\Pythonwin
C:/Users/ja/AppData/Roaming/QGIS/QGIS3\profiles\default/python
C:/Alles/works/maps/vizka/podkl

ccrook / QGIS-Contour-Plugin

Option "Fixed contour interval" crashes in QGIS 3 #29