FIX: create _dashSeq and _dashOfset before use

closes matplotlib#5850

Author: tacaswell

lib/matplotlib/lines.py

@@ -332,6 +332,10 @@ def __init__(self, xdata, ydata,
         self._linestyles = None
         self._drawstyle = None
         self._linewidth = None
+
+        self._dashSeq = None
+        self._dashOffset = 0
+
         self.set_linestyle(linestyle)
         self.set_drawstyle(drawstyle)
         self.set_linewidth(linewidth)
@@ -349,9 +353,6 @@ def __init__(self, xdata, ydata,
         self.set_antialiased(antialiased)
         self.set_markersize(markersize)
 
-        self._dashSeq = None
-        self._dashOffset = 0
-
         self._markeredgecolor = None
         self._markeredgewidth = None
         self._markerfacecolor = None