Debug Full Stack
Error: Instances of UndefinedObject are not indexable

    * UndefinedObject(Object)>>error:

          self	nil
          temps
          aString	'Instances of UndefinedObject are not indexable'

    * UndefinedObject(Object)>>errorNotIndexable

          self	nil
          temps

    * UndefinedObject(Object)>>size

          self	nil
          temps

    * [] in BLMBookImportComponent>>renderContentOn: {[isbnValue size < 10 ifTrue: [self lightbox: (WAFormDialog new addMess...]}

          self	a BLMBookImportComponent
          temps
          html	nil
          titleValue	nil
          isbnValue	nil
          val	nil
          inst vars
          decoration	a WAStateHolder(a BLMBookImportComponent)

    * WAActionCallback>>evaluateWithArgument:

          self	a WAActionCallback
          temps
          anObject	'importieren'
          inst vars
          context	a WARenderingContext
          owner	a BLMBookImportComponent
          key	'3'
          block	[] in BLMBookImportComponent>>renderContentOn: {[isbnValue size < 10 ifTrue: [self lightbox: (...etc...