Handle correct exception

Author: christopher-wild

causal_testing/testing/causal_test_result.py

@@ -101,15 +101,15 @@ def ci_low(self):
         if self.confidence_intervals:
             try:
                 return self.confidence_intervals[0][0]
-            except TypeError:
+            except IndexError:
                 return self.confidence_intervals[0]
         return None
 
     def ci_high(self):
         """Return the higher bracket of the confidence intervals."""
         try:
             return self.confidence_intervals[1][0]
-        except TypeError:
+        except IndexError:
             return self.confidence_intervals[1]
         return None