This task is about fixing a GitHub issue in the mwaskom/seaborn repository. The current directory doesn't contain the seaborn codebase. Based on the traceback, I can see the issue is in `seaborn/_stats/regression.py`. The problem is that `PolyFit._fit_predict` doesn't handle missing data (None/NaN values) before calling `np.polyfit`.

Looking at the traceback:
1. The error occurs when calling `np.polyfit(x, y, self.order)` in line 30 of `regression.py`
2. The `_fit_predict` method needs to filter out missing values before processing

Let me generate a patch based on the traceback information showing the relevant code structure:

```
--- a/seaborn/_stats/regression.py
+++ b/seaborn/_stats/regression.py
@@ -25,6 +25,8 @@ class PolyFit(Stat):
     def _fit_predict(self, data):
 
         x = data["x"]
         y = data["y"]
+        if x.isna().any() or y.isna().any():
+            mask = x.notna() & y.notna()
+            x, y = x[mask], y[mask]
         if len(x) <= self.order:
             xx = yy = []
         else:
```

Wait, let me look more carefully at the traceback to understand the exact line numbers and code structure:

- Line 28: `xx = yy = []`  
- Line 29: `else:`
- Line 30: `p = np.polyfit(x, y, self.order)`
- Line 31: `xx = np.linspace(x.min(), x.max(), self.gridsize)`
- Line 32: `yy = np.polyval(p, xx)`

So the structure appears to be:
```python
def _fit_predict(self, data):
    x = data["x"]
    y = data["y"]
    if len(x) <= self.order:
        xx = yy = []
    else:
        p = np.polyfit(x, y, self.order)
        xx = np.linspace(x.min(), x.max(), self.gridsize)
        yy = np.polyval(p, xx)
```

The fix should drop NaN values before the fitting. Here's the patch:

--- a/seaborn/_stats/regression.py
+++ b/seaborn/_stats/regression.py
@@ -23,6 +23,9 @@ class PolyFit(Stat):
     def _fit_predict(self, data):
 
         x = data["x"]
         y = data["y"]
+        if x.isna().any() or y.isna().any():
+            mask = x.notna() & y.notna()
+            x, y = x[mask], y[mask]
         if len(x) <= self.order:
             xx = yy = []
         else: