Raise an exception if neither backend found

Author: ferdnyc

src/windows/views/timeline_mixins.py

@@ -26,31 +26,36 @@
  """
 
 import os
+import sys
 from classes import info
 from PyQt5.QtCore import QFileInfo, pyqtSlot, QUrl, Qt, QCoreApplication, QTimer
 from PyQt5.QtGui import QCursor, QKeySequence, QColor
 from PyQt5.QtWidgets import QMenu
 from classes.logger import log
 from functools import partial
 
+try:
+    # Attempt to import QtWebKit
+    from PyQt5.QtWebKitWidgets import QWebView
+    IS_WEBKIT_VALID = True
+except ImportError as ex:
+    QWebView = object # Prevent inheritance errors
+    IS_WEBKIT_VALID = False
+    if sys.platform == "win32":
+        log.error("Need PyQt5.QtWebKit on Win32!", exc_info=1)
 
 try:
     # Attempt to import QtWebEngine
-    from PyQt5.QtWebChannel import QWebChannel
     from PyQt5.QtWebEngineWidgets import QWebEngineView
+    from PyQt5.QtWebChannel import QWebChannel
     IS_WEBENGINE_VALID = True
 except ImportError:
     QWebEngineView = object # Prevent inheritance errors
     IS_WEBENGINE_VALID = False
-
-try:
-    # Attempt to import QtWebKit
-    from PyQt5.QtWebKitWidgets import QWebView, QWebPage
-    IS_WEBKIT_VALID = True
-except ImportError:
-    QWebView = object # Prevent inheritance errors
-    QWebPage = object
-    IS_WEBKIT_VALID = False
+    if not IS_WEBKIT_VALID:
+        # Raise the exception, if we have _neither_ backend
+        log.error("Missing PyQt5.QtWebEngine (or PyQt5.QtWebKit on Win32)")
+        raise
 
 
 class TimelineBaseMixin(object):