Check for dependencies before loading

novelWriter.py

@@ -2,7 +2,33 @@
 # -*- coding: utf-8 -*-
 
 import sys
-import nw
+
+try:
+    import PyQt5.QtWidgets
+    import PyQt5.QtGui
+    import PyQt5.QtCore
+except:
+    print("ERROR: Failed to load dependency python3-pyqt5")
+    exit(1)
+
+try:
+    import lxml
+except:
+    print("ERROR: Failed to load dependency python3-lxml")
+    exit(1)
+
+try:
+    import appdirs
+except:
+    print("ERROR: Failed to load dependency python3-appdirs")
+    exit(1)
+
+try:
+    import enchant
+except:
+    print("ERROR: Failed to load dependency python3-enchant")
+    exit(1)
 
 if __name__ == "__main__":
+    import nw
     nw.main(sys.argv[1:])