check input channel

Author: RandyShuai

tf2onnx/onnx_opset/nn.py

@@ -284,6 +284,8 @@ def version_1(cls, ctx, node, **kwargs):
         if len(kernel_shape) != 4:
             raise ValueError("only Conv2D is supported")
         k_h, k_w, k_input_channels, k_channel_multiplier = kernel_shape
+        if k_input_channels < 1:
+            raise ValueError("input channel must be positive")
         k_output_channels = k_input_channels  * k_channel_multiplier
 
         node.set_attr("kernel_shape", [k_h, k_w])