[BUG] Auto-completion issues (list)

[georg-schwarz]

• [ ] completion first constraint reference in value type works, later ones don't
• [ ] completion of block type name in block throws error (TypeError: Cannot read properties of undefined (reading 'ref'))
• [ ] completion of column value types in blocks oftype TableInterpreter don't show completion items
• [ ] completion of block properties shows all referenceable elements instead of the ones with the right type
• [ ] completion of pipes shows blocks that are not connectable (wrong input type)