diff --git a/core/nodeslicer/nodes/base.py b/core/nodeslicer/nodes/base.py
index 73a3ae0..829315e 100644
--- a/core/nodeslicer/nodes/base.py
+++ b/core/nodeslicer/nodes/base.py
@@ -78,8 +78,8 @@ class MathNode(SliceNode):
     def evaluate_output(self, socket_name: str, **_kwargs) -> math_type:
         t = self.math_type
 
-        a: t = resolve_input(self.inputs[0])
-        b: t = resolve_input(self.inputs[1])
+        a: t = resolve_input(self.inputs[0]) or 0
+        b: t = resolve_input(self.inputs[1]) or 0
 
         op = self.operation
         try:
diff --git a/core/nodeslicer/nodes/gcode.py b/core/nodeslicer/nodes/gcode.py
index 7831000..084adc8 100644
--- a/core/nodeslicer/nodes/gcode.py
+++ b/core/nodeslicer/nodes/gcode.py
@@ -175,7 +175,8 @@ class SLICENODE_JoinGcode(SliceNodeJoiner):
         from ....infra.blender.blender_slice_nodes_generic import resolve_input
         gcode_input: list[str] = []
         for input in self.inputs:
-            gcode_input += [resolve_input(input)] or [""]
+            gc: str = str(resolve_input(input))
+            gcode_input += [gc] or [""]
         return "\n".join(gcode_input)
 
 @register_class
diff --git a/core/nodeslicer/nodes/mesh.py b/core/nodeslicer/nodes/mesh.py
index ec3f95c..6f863f7 100644
--- a/core/nodeslicer/nodes/mesh.py
+++ b/core/nodeslicer/nodes/mesh.py
@@ -39,7 +39,7 @@ class SLICENODE_JoinMesh(SliceNodeJoiner):
 
     def evaluate_output(self, socket_name: str, **_kwargs) -> SlicingCollection:
         from ....infra.blender.blender_slice_nodes_generic import resolve_input
-        merged_coll = resolve_input(self.inputs[0])
+        merged_coll = resolve_input(self.inputs[0]) or SlicingCollection([],'')
         
         for input in self.inputs[1:]:
             coll = resolve_input(input)