check None in check_if_negative

Author: Kislovskiy

lib/matplotlib/axes/_axes.py

@@ -3285,20 +3285,16 @@ def errorbar(self, x, y, yerr=None, xerr=None,
             raise ValueError("'x' and 'y' must have the same size")
 
         def check_if_negative(array):
+            if array is None:
+                return False
             try:
                 if np.any(array < 0):
                     return True
             except TypeError:   # Don't fail on 'datetime.*' types
                 pass
 
-        if xerr is not None and check_if_negative(xerr):
-            if yerr is not None and check_if_negative(yerr):
-                raise ValueError(
-                    "'xerr' and 'yerr' must have positive numbers")
-            else:
-                raise ValueError("'xerr' must have positive numbers")
-        if check_if_negative(yerr):
-            raise ValueError("'yerr' must have positive numbers")
+        if check_if_negative(xerr) or check_if_negative(yerr):
+            raise ValueError("'xerr' and 'yerr' must have positive numbers")
 
         if isinstance(errorevery, Integral):
             errorevery = (0, errorevery)

lib/matplotlib/tests/test_axes.py

@@ -3519,9 +3519,11 @@ def test_xerr_yerr_positive():
     with pytest.raises(ValueError,
                        match="'xerr' and 'yerr' must have positive numbers"):
         ax.errorbar(x=[0], y=[0], xerr=[[-0.5], [1]], yerr=[[-0.5], [1]])
-    with pytest.raises(ValueError, match="'xerr' must have positive numbers"):
+    with pytest.raises(ValueError,
+                        match="'xerr' and 'yerr' must have positive numbers"):
         ax.errorbar(x=[0], y=[0], xerr=[[-0.5], [1]])
-    with pytest.raises(ValueError, match="'yerr' must have positive numbers"):
+    with pytest.raises(ValueError,
+                        match="'xerr' and 'yerr' must have positive numbers"):
         ax.errorbar(x=[0], y=[0], yerr=[[-0.5], [1]])