Fix NaNs in pdf output breaking rendering

Avoids propagation of NaNs into the output PDF files via the impact error bars by flipping comparisons such that the always falsey comparison with NaN results into the default values.

This caused rendering issues on some platforms, e.g.:

dhi/plots/pulls_impacts.py

@@ -272,8 +272,8 @@ def plot_pulls_impacts(
             # place points always on zero, set errors to act as impact values
             g_impact_hi.SetPoint(idx, 0, idx - 0.5)
             g_impact_lo.SetPoint(idx, 0, idx - 0.5)
-            g_impact_hi.SetPointError(idx, 0 if u > 0 else -u, u if u > 0 else 0, 0.5, 0.5)
-            g_impact_lo.SetPointError(idx, -d if d < 0 else 0, 0 if d < 0 else d, 0.5, 0.5)
+            g_impact_hi.SetPointError(idx, -u if u < 0 else 0, u if u > 0 else 0, 0.5, 0.5)
+            g_impact_lo.SetPointError(idx, -d if d < 0 else 0, d if d > 0 else 0, 0.5, 0.5)
             # fill overlap graph with up values in case of equal signs and larger down impact
             if u * d > 0 and abs(d) > abs(u):
                 g_impact_overlap.SetPoint(idx, 0, idx - 0.5)