Add more explicit error message for [r,theta]grids

ksunden · ksunden · commit 10d2225cc1e4 · 2023-03-30T12:31:22.000-05:00
mypy was unhappy because the first parameter in each case (angles/radii) is optional for the pyplot wrapper but required for the set_[r,theta]grids axes methods. The variable is optional because the pyplot version acts as both the getter and the setter, but the type is not sufficiently narrowed for mypy. If passed None, the underlying setters would error, though deeper in the stack either in numpy or upon setting ticks. Just be a bit more explicit and fail early with a targetted error message
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -2104,6 +2104,8 @@ def rgrids(
     if all(p is None for p in [radii, labels, angle, fmt]) and not kwargs:
         lines_out: list[Line2D] = ax.yaxis.get_gridlines()
         labels_out: list[Text] = ax.yaxis.get_ticklabels()
+    elif radii is None:
+        raise TypeError("'radii' cannot be None when other parameters are passed")
     else:
         lines_out, labels_out = ax.set_rgrids(
             radii, labels=labels, angle=angle, fmt=fmt, **kwargs)
@@ -2177,6 +2179,8 @@ def thetagrids(
     if all(param is None for param in [angles, labels, fmt]) and not kwargs:
         lines_out: list[Line2D] = ax.xaxis.get_ticklines()
         labels_out: list[Text] = ax.xaxis.get_ticklabels()
+    elif angles is None:
+        raise TypeError("'angles' cannot be None when other parameters are passed")
     else:
         lines_out, labels_out = ax.set_thetagrids(angles,
                                                   labels=labels, fmt=fmt,
