Tidy some control flow.

diffoscope/config.py

@@ -76,23 +76,23 @@ class Config:
         va = getattr(self, a)
         vb = getattr(self, b)
         if va < vb:
-            if isinstance(vb, defaultint):
-                logger.warning(
-                    "%s (%s) < default value of %s (%s), setting latter to %s",
-                    a,
-                    va,
-                    b,
-                    vb,
-                    va,
-                )
-                setattr(self, b, va)
-            else:
+            if not isinstance(vb, defaultint):
                 raise ValueError(
                     "{0} ({1}) cannot be smaller than {2} ({3})".format(
                         a, va, b, vb
                     )
                 )
 
+            logger.warning(
+                "%s (%s) < default value of %s (%s), setting latter to %s",
+                a,
+                va,
+                b,
+                vb,
+                va,
+            )
+            setattr(self, b, va)
+
     def check_constraints(self):
         self.check_ge("max_diff_block_lines", "max_page_diff_block_lines")
         self.check_ge("max_report_size", "max_page_size")