added a try and catch block

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "githubPullRequests.ignoredPullRequestBranches": [
+        "master"
+    ]
+}

fipy/meshes/nonUniformGrid1D.py

@@ -39,8 +39,12 @@ def __init__(self, dx=1., nx=None, overlap=2,
                  _RepresentationClass=_Grid1DRepresentation,
                  _TopologyClass=_Grid1DTopology):
 
-        if not isinstance(nx, int) or nx < 0:
-            raise ValueError("nx must be a non-negative integer")
+        try:
+            if not isinstance(nx, int) or nx < 0:
+                raise ValueError("nx must be a non-negative integer")
+        except ValueError as e:
+            print(f"Error: {e}")
+            raise
 
         builder = _BuilderClass()
 

fipy/meshes/nonUniformGrid2D.py

@@ -22,8 +22,12 @@ class NonUniformGrid2D(Mesh2D):
     """
     def __init__(self, dx=1., dy=1., nx=None, ny=None, overlap=2, communicator=parallelComm,
                  _RepresentationClass=_Grid2DRepresentation, _TopologyClass=_Grid2DTopology):
-        if (not isinstance(nx, int) or nx < 0) and (not isinstance(ny, int) or ny < 0):
-            raise ValueError("nx must be a non-negative integer")
+        try:
+            if (not isinstance(nx, int) or nx < 0) and (not isinstance(ny, int) or ny < 0):
+                raise ValueError("nx must be a non-negative integer")
+        except ValueError as e:
+            print(f"Error: {e}")
+            raise
 
         builder = _NonuniformGrid2DBuilder()
 

fipy/meshes/nonUniformGrid3D.py

@@ -31,9 +31,13 @@ class NonUniformGrid3D(Mesh):
     """
     def __init__(self, dx = 1., dy = 1., dz = 1., nx = None, ny = None, nz = None, overlap=2, communicator=parallelComm,
                  _RepresentationClass=_Grid3DRepresentation, _TopologyClass=_Grid3DTopology):
-
-        if (not isinstance(nx, int) or nx < 0) and (not isinstance(ny, int) or ny < 0) and (not isinstance(nz, int) or nz < 0):
-            raise ValueError("nx must be a non-negative integer")
+
+        try:
+            if (not isinstance(nx, int) or nx < 0) and (not isinstance(ny, int) or ny < 0) and (not isinstance(nz, int) or nz < 0):
+                raise ValueError("nx must be a non-negative integer")
+        except ValueError as e:
+            print(f"Error: {e}")
+            raise
 
         builder = _NonuniformGrid3DBuilder()