Draft: Prevented error when grid size is zero - issue #5427

src/Mod/Draft/draftguitools/gui_trackers.py

@@ -1059,6 +1059,19 @@ class gridTracker(Tracker):
         """Redraw the grid."""
         # Resize the grid to make sure it fits
         # an exact pair number of main lines
+        if self.space == 0:
+            self.lines1.numVertices.deleteValues(0)
+            self.lines2.numVertices.deleteValues(0)
+            FreeCAD.Console.PrintWarning("Draft Grid: Spacing value is zero\n")
+            return
+        if self.mainlines == 0:
+            self.lines1.numVertices.deleteValues(0)
+            self.lines2.numVertices.deleteValues(0)
+            return
+        if self.numlines == 0:
+            self.lines1.numVertices.deleteValues(0)
+            self.lines2.numVertices.deleteValues(0)
+            return
         numlines = self.numlines // self.mainlines // 2 * 2 * self.mainlines
         bound = (numlines // 2) * self.space
         border = (numlines//2 + self.mainlines/2) * self.space