Check if variable is BitVec before copying annotations

mythril/laser/ethereum/instructions.py

@@ -946,6 +946,7 @@ class Instruction:
             annotations = []
 
             for b in state.memory[index : index + length]:
+                if isinstance(b, BitVec):
                     annotations.append(b.annotations)
 
             argument_str = str(state.memory[index]).replace(" ", "_")