Scratch

Right, so I just attempted to add a load of variable blocks from panther into my scratch Mod, but upon closing and reopening the scratch window I get the following error:

Symbol(Object)>>error:
Symbol(Object)>>doesNotUnderstand:
[] in ScratchSpriteMorph(ScriptableScratchMorph)>>addGenericVariableBlocksTo:x:y:
Array(SequenceableCollection)>>do:
ScratchSpriteMorph(ScriptableScratchMorph)>>addGenericVariableBlocksTo:x:y:
ScratchSpriteMorph(ScriptableScratchMorph)>>variablesPage
ScratchSpriteMorph(ScriptableScratchMorph)>>viewerPageForCategory:
ScratchViewerMorph>>updateContents
ScratchViewerMorph>>categoryChanged:
ScratchStageMorph(ScriptableScratchMorph)>>addVariable:

From reading it I assume it has something to do with this section, but then again I'm a noob so I have no idea....

addVariable: varName
    "Add a new user variable with the given name to this object. Do nothing if the variable already exists or is built in."
   
    | sFrame stage isGlobal |
    isGlobal _ false.
    (sFrame _ self ownerThatIsA: ScratchFrameMorph) ifNil: [
        (sFrame _ self ownerThatIsA: OffscreenWorldMorph) ifNotNil: [
            sFrame _ sFrame frame.
            stage _ sFrame workPane.
            isGlobal _ stage varNames includes: varName asString.
            ((vars includesKey: varName asString) or: [isGlobal = true]) ifFalse: [
                vars at: varName asString put: 0.
            ].
        ].
    ]
    ifNotNil: [
        (stage _ self ownerThatIsA: ScratchStageMorph)
            ifNotNil: [isGlobal _ stage varNames includes: varName asString].
        ((vars includesKey: varName asString) or: [isGlobal = true]) ifFalse: [
            vars at: varName asString put: 0].
        sFrame viewerPane categoryChanged: 'variables'.].

Any help is much appreciated