I expect to be able to craft dispensers while retaining my enchanted bows.
What happened was that crafting dispensers used my enchanted bow even though I had normal bows in my inventory.
If it's not a bug to be able to craft a dispenser using an enchanted bow, I should be able to have more control over which bow should be used to craft the dispenser so I don't lose the enchantments I worked hard to obtain.
Thank you for your report! This issue was, however, reported at an earlier time as MCPE-10159. Feel free to add any information you find relevant in the comment section there.