Moved some package checks into the main function so we can pop an error dialog for non-command line users.

nw/__init__.py

@@ -32,7 +32,7 @@ import logging
 from os import path, remove, rename
 
 from PyQt5.QtGui import QIcon
-from PyQt5.QtWidgets import QApplication
+from PyQt5.QtWidgets import QApplication, QErrorMessage
 
 from nw.guimain import GuiMain
 from nw.config import Config
@@ -217,6 +217,43 @@ def main(sysArgs=None):
 
     logger.setLevel(debugLevel)
 
+    # Check Packages and Versions
+    errorData = []
+    if sys.hexversion < 0x030600F0:
+        errorData.append(
+            "At least Python 3.6 is required."
+        )
+    if CONFIG.verQtValue < 50200:
+        errorData.append(
+            "At least Qt5 version 5.2 is required, found %s." % CONFIG.verQtString
+        )
+    if CONFIG.verPyQtValue < 50200:
+        errorData.append(
+            "At least PyQt5 version 5.2 is required, found %s." % CONFIG.verPyQtString
+        )
+    try:
+        import PyQt5.QtSvg
+    except:
+        errorData.append("Python module 'PyQt5.QtSvg' is missing.")
+    try:
+        import lxml
+    except:
+        errorData.append("Python module 'lxml' is missing.")
+
+    if errorData:
+        errApp = QApplication([])
+        errMsg = QErrorMessage()
+        errMsg.setMinimumWidth(500)
+        errMsg.setMinimumHeight(300)
+        errMsg.showMessage((
+            "ERROR: %s cannot start due to the following issues:<br><br>"
+            "&nbsp;-&nbsp;%s<br><br>Exiting."
+        ) % (
+            __package__, "<br>&nbsp;-&nbsp;".join(errorData)
+        ))
+        errApp.exec_()
+        sys.exit(1)
+
     CONFIG.initConfig(confPath, dataPath)
 
     if testMode:

nw/config.py

@@ -36,6 +36,7 @@ from time import time
 
 from PyQt5.Qt import PYQT_VERSION_STR
 from PyQt5.QtCore import QT_VERSION_STR, QStandardPaths, QSysInfo
+from PyQt5.QtWidgets import QErrorMessage
 
 from nw.constants import nwFiles, nwUnicode
 from nw.common import splitVersionNumber, formatTimeStamp