Add NaN/Inf checks into check_numpy_array_features

For normal scenario (and provide a killer switch to turn off the check), all numpy arrays should not have NaN or Inf.

course/page/code_feedback.py

@@ -64,7 +64,7 @@ def check_numpy_array_sanity(self, name, num_axes, data):
                     0, f"'{name}' does not consist of floating point numbers--"
                     f"got: '{data.dtype}'")
 
-    def check_numpy_array_features(self, name, ref, data, report_failure=True):
+    def check_numpy_array_features(self, name, ref, data, report_failure=True, check_finite=True):
         import numpy as np
         assert isinstance(ref, np.ndarray)
 
@@ -91,6 +91,12 @@ def bad(msg):
                     f"'{name}' does not have correct data type--"
                     f"got: '{data.dtype}', expected: '{ref.dtype}'")
 
+        if check_finite:
+            if np.any(np.isnan(data)):
+                return bad(f"'{name}' contains NaN")
+            if np.any(np.isinf(data)):
+                return bad(f"'{name}' contains Inf")
+
         return True
 
     def check_numpy_array_allclose(self, name, ref, data, accuracy_critical=True,