Non mob entities should have loot tables, if they drop loot.
Fixing them may also mean adding the DeathLootTable and DeathLootTable tags to said entities (or having these tags in the main entity class, and not Living).
Note: that MCPE's addons have one for the boat
Affects:

• boat
• minecart
• chest_minecart
• furnace_minecart
• hopper_minecart
• tnt_minecart
• spawner_minecart
• command_block_minecart
• armor_stand ^{Added in 18w44a}
• painting
• item_frame
• eye_of_ender
• leash_knot

The following don't drop loot, but, if added, gives map makers more possibilities:

• item
• experience_orb
• arrow
• dragon_fireball
• fireball
• small_fireball
• snowball
• spectral_arrow
• egg
• ender_pearl
• experience_bottle
• potion
• wither_skull
• tnt
• falling_block
• area_effect_cloud
• end_crystal
• evoker_fangs
• firework_rocket
• shulker_bullet
• llama_spit