Add check for dims of x and y in model.fit.

src/TensorFlowNET.Keras/Engine/Model.Fit.cs

@@ -31,6 +31,11 @@ namespace Tensorflow.Keras.Engine
             int workers = 1,
             bool use_multiprocessing = false)
         {
+            if (x.dims[0] != y.dims[0])
+            {
+                throw new InvalidArgumentError(
+                    $"The array x and y should have same value at dim 0, but got {x.dims[0]} and {y.dims[0]}");
+            }
             int train_count = Convert.ToInt32(x.dims[0] * (1 - validation_split));
             var train_x = x[new Slice(0, train_count)];
             var train_y = y[new Slice(0, train_count)];