Add more checks and panics

crates/burn-import/src/onnx/op_configuration.rs

@@ -747,23 +747,28 @@ pub fn layer_norm_config(node: &Node) -> (LayerNormConfig, bool) {
 
 /// Create a PadConfig from the attributes of the node
 pub fn pad_config(node: &Node) -> PadConfig {
+    fn check_inputs(node: &Node) {
+        if node.inputs.len() == 1 {
+            panic!("Pad: must provide at least two inputs")
+        }
+    }
     fn get_pads(node: &Node) -> Vec<usize> {
         let input_dim = match &node.inputs.first().unwrap().ty {
             ArgType::Tensor(tensor) => tensor.dim,
-            _ => panic!("Only tensor input is valid"),
+            _ => panic!("Pad: Only tensor input is valid"),
         };
         let pads: Vec<usize> = match &node.inputs[1].value {
             Some(Data::Int64s(shape)) => shape
                 .iter()
                 .map(|&x| {
                     if x < 0 {
                         // TODO: support negative pads
-                        panic!("Negative pad is not supported");
+                        panic!("Pad: Negative pad is not supported");
                     }
                     x as usize
                 })
                 .collect(),
-            _ => panic!("Pads data type must be int64"),
+            _ => panic!("Pad: pads data type must be int64"),
         };
 
         assert_eq!(pads.len(), input_dim * 2);
@@ -778,13 +783,22 @@ pub fn pad_config(node: &Node) -> PadConfig {
             vec![left, right, top, bottom]
         }
     }
+    fn get_constant_value(node: &Node) -> f32 {
+        // TODO: support int, boolean
+        if node.inputs.len() < 3 {
+            0.
+        } else {
+            match &node.inputs[2].value {
+                Some(Data::Float32s(shape)) => shape.first().unwrap().to_owned(),
+                _ => 0.,
+            }
+        }
+    }
 
+    check_inputs(node);
     let pads = get_pads(node);
-    // TODO: support int, boolean
-    let constant_value: f32 = match &node.inputs[2].value {
-        Some(Data::Float32s(shape)) => shape.first().unwrap().to_owned(),
-        _ => 0.,
-    };
+    let constant_value = get_constant_value(node);
+
     PadConfig::new(pads, constant_value)
 }