>I have been beset by some trait strangeness. ...
> In between were some round trips to monticello ...

I started a fresh 3.9 dev image and tried to load my code with traits from 
monticello, got an error when monticello got to my trait.

Ideas?

Thanks - Sophie

==============

VM: Win32 - a SmalltalkImage
Image: Squeak3.9.1 [latest update: #7075]

UndefinedObject(Object)>>doesNotUnderstand: #select:thenCollect:
 Receiver: nil
 Arguments and temporary variables:
  aMessage:  select: [] in MCClassDefinition>>selectVariables: {[:v | v 
perform: a...etc...
 Receiver's instance variables:
nil

MCClassDefinition>>selectVariables:
 Receiver: a MCClassDefinition(TMyTrait)
 Arguments and temporary variables:
  aSelector:  #isPoolImport
  v:  nil
 Receiver's instance variables:
  name:  #TMyTrait
  superclassName:  nil
  variables:  nil
  category:  'MP-Views2'
  type:  nil
  comment:  ''
  commentStamp:  ''
  traitComposition:  nil
  classTraitComposition:  nil

MCClassDefinition>>poolDictionaries
 Receiver: a MCClassDefinition(TMyTrait)
 Arguments and temporary variables:

 Receiver's instance variables:
  name:  #TMyTrait
  superclassName:  nil
  variables:  nil
  category:  'MP-Views2'
  type:  nil
  comment:  ''
  commentStamp:  ''
  traitComposition:  nil
  classTraitComposition:  nil

MCClassDefinition>>requirements
 Receiver: a MCClassDefinition(TMyTrait)
 Arguments and temporary variables:

 Receiver's instance variables:
  name:  #TMyTrait
  superclassName:  nil
  variables:  nil
  category:  'MP-Views2'
  type:  nil
  comment:  ''
  commentStamp:  ''
  traitComposition:  nil
  classTraitComposition:  nil


--- The full stack ---
UndefinedObject(Object)>>doesNotUnderstand: #select:thenCollect:
MCClassDefinition>>selectVariables:
MCClassDefinition>>poolDictionaries
MCClassDefinition>>requirements
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
MCDependencySorter>>unresolvedRequirementsFor:
MCDependencySorter>>add:
[] in MCDependencySorter>>addAll: {[:ea | self add: ea]}
Array(SequenceableCollection)>>do:
MCDependencySorter>>addAll:
MCDependencySorter class>>items:
MCDependencySorter class>>sortItems:
MCStWriter>>writeDefinitions:
MCMczWriter>>serializeDefinitions:
MCMczWriter>>writeSnapshot:
MCMczWriter>>writeDefinitions:
MCMczWriter>>writeVersion:
MCMczWriter class>>fileOut:on:
MCVersion>>fileOutOn:
[] in MCCacheRepository(MCFileBasedRepository)>>basicStoreVersion: {[:s | 
aVersion fileOutOn: s]}
MCCacheRepository(MCDirectoryRepository)>>writeStreamForFileNamed:replace:do:
MCCacheRepository(MCFileBasedRepository)>>writeStreamForFileNamed:do:
MCCacheRepository(MCFileBasedRepository)>>basicStoreVersion:
MCCacheRepository>>basicStoreVersion:
MCCacheRepository(MCRepository)>>storeVersion:
MCVersion>>addToCache
MCVersion>>initializeWithPackage:info:snapshot:dependencies:
MCVersion class>>package:info:snapshot:dependencies:
MCMczReader(MCVersionReader)>>basicVersion
MCMczReader(MCVersionReader)>>version
[] in 
MCDirectoryRepository(MCFileBasedRepository)>>loadVersionFromFileNamed: {[:r 
| r version]}
[] in 
MCDirectoryRepository(MCFileBasedRepository)>>versionReaderForFileNamed:do: 
{[:class | aBlock   value: (class on: s fileName: aString)]}
MCMczReader class(Object)>>ifNotNilDo:
[] in 
MCDirectoryRepository(MCFileBasedRepository)>>versionReaderForFileNamed:do: 
{[:s | (MCVersionReader readerClassForFileNamed: aString)   ifNotNilDo: 
[:cla...]}
MCDirectoryRepository>>readStreamForFileNamed:do:
MCDirectoryRepository(MCFileBasedRepository)>>versionReaderForFileNamed:do:
MCDirectoryRepository(MCFileBasedRepository)>>loadVersionFromFileNamed:
[] in MCDirectoryRepository(MCFileBasedRepository)>>versionFromFileNamed: 
{[self loadVersionFromFileNamed: aString]}
Dictionary>>at:ifAbsent:
MCDirectoryRepository(MCFileBasedRepository)>>versionFromFileNamed:
[] in MCFileRepositoryInspector>>version {[version := repository 
versionFromFileNamed: selectedVersion]}
BlockContext>>ensure:
CursorWithMask(Cursor)>>showWhile:
MCFileRepositoryInspector>>version
MCFileRepositoryInspector>>load
PluggableButtonMorphPlus(PluggableButtonMorph)>>performAction
PluggableButtonMorphPlus>>performAction
[] in PluggableButtonMorphPlus(PluggableButtonMorph)>>mouseUp: {[:m | (m 
containsPoint: evt cursorPoint)   ifTrue: [m performAction]]}
Array(SequenceableCollection)>>do:
...etc...