Change documented default value of nonpositive parameter

The default value of nonpositive is falsely documented as 'mask' instead of 'clip'. This was fixed for the loglog function but needed to be fixed for semilogx and semilogy as well.

Author: pettza

lib/matplotlib/axes/_axes.py

@@ -1892,7 +1892,7 @@ def semilogx(self, *args, **kwargs):
             are automatically chosen depending on the number of decades in the
             plot. See `.Axes.set_xscale` for details.
 
-        nonpositive : {'mask', 'clip'}, default: 'mask'
+        nonpositive : {'mask', 'clip'}, default: 'clip'
             Non-positive values in x can be masked as invalid, or clipped to a
             very small positive number.
 
@@ -1939,7 +1939,7 @@ def semilogy(self, *args, **kwargs):
             are automatically chosen depending on the number of decades in the
             plot. See `.Axes.set_yscale` for details.
 
-        nonpositive : {'mask', 'clip'}, default: 'mask'
+        nonpositive : {'mask', 'clip'}, default: 'clip'
             Non-positive values in y can be masked as invalid, or clipped to a
             very small positive number.