Remove pass if we have a docstring

Lib/fontTools/varLib/errors.py

@@ -115,32 +115,22 @@ class FoundANone(VarLibMergeError):
 class MismatchedTypes(VarLibMergeError):
     """data had inconsistent types"""
 
-    pass
-
 
 class LengthsDiffer(VarLibMergeError):
     """a list of objects had inconsistent lengths"""
 
-    pass
-
 
 class KeysDiffer(VarLibMergeError):
     """a list of objects had different keys"""
 
-    pass
-
 
 class InconsistentGlyphOrder(VarLibMergeError):
     """the glyph order was inconsistent between masters"""
 
-    pass
-
 
 class InconsistentExtensions(VarLibMergeError):
     """the masters use extension lookups in inconsistent ways"""
 
-    pass
-
 
 class UnsupportedFormat(VarLibMergeError):
     """an OpenType subtable (%s) had a format I didn't expect"""
@@ -154,7 +144,6 @@ class UnsupportedFormat(VarLibMergeError):
 class UnsupportedFormat(UnsupportedFormat):
     """an OpenType subtable (%s) had inconsistent formats between masters"""
 
-    pass
 
 class VarLibCFFMergeError(VarLibError):
     pass