diff --git a/programs/move_loader_api/src/account_state.rs b/programs/move_loader_api/src/account_state.rs
index b43f893d29..bff1f4576c 100644
--- a/programs/move_loader_api/src/account_state.rs
+++ b/programs/move_loader_api/src/account_state.rs
@@ -1,4 +1,4 @@
-#![allow(dead_code)]
+//! Helpers to create Libra accounts for testing
 
 use crate::data_store::DataStore;
 use compiler::Compiler;
@@ -78,6 +78,7 @@ impl LibraAccountState {
         let arena = Arena::new();
         let state_view = DataStore::default();
         let vm_cache = VMModuleCache::new(&arena);
+        // Libra enforces the mint address to be 0x0 (see Libra's `mint_to_address` function)
         let mint_address = AccountAddress::default();
         // TODO: Need this?
         let genesis_auth_key = ByteArray::new(mint_address.to_vec());
diff --git a/programs/move_loader_api/src/data_store.rs b/programs/move_loader_api/src/data_store.rs
index 6ad8a0d6a3..4967012932 100644
--- a/programs/move_loader_api/src/data_store.rs
+++ b/programs/move_loader_api/src/data_store.rs
@@ -44,7 +44,7 @@ impl DataStore {
     }
 
     /// Returns a `WriteSet` for each account in the `DataStore`
-    pub fn into_write_sets(mut self) -> HashMap<AccountAddress, WriteSet> {
+    pub fn into_write_sets(mut self) -> Result<HashMap<AccountAddress, WriteSet>> {
         let mut write_set_muts: HashMap<AccountAddress, WriteSetMut> = HashMap::new();
         for (access_path, value) in self.data.drain() {
             match write_set_muts.get_mut(&access_path.address) {
@@ -60,9 +60,9 @@ impl DataStore {
         // Freeze each WriteSet
         let mut write_sets: HashMap<AccountAddress, WriteSet> = HashMap::new();
         for (address, write_set_mut) in write_set_muts.drain() {
-            write_sets.insert(address, write_set_mut.freeze().unwrap());
+            write_sets.insert(address, write_set_mut.freeze()?);
         }
-        write_sets
+        Ok(write_sets)
     }
 
     /// Read an account's resource
diff --git a/programs/move_loader_api/src/processor.rs b/programs/move_loader_api/src/processor.rs
index 9ba0ef1ab0..d4d0291ac0 100644
--- a/programs/move_loader_api/src/processor.rs
+++ b/programs/move_loader_api/src/processor.rs
@@ -86,7 +86,13 @@ impl MoveProcessor {
     }
     fn map_vm_binary_error(err: vm::errors::BinaryError) -> InstructionError {
         debug!("Error: Script deserialize failed: {:?}", err);
-        InstructionError::GenericError
+        InstructionError::InvalidInstructionData
+    }
+    fn map_vm_verification_error(
+        err: std::vec::Vec<vm::errors::VerificationStatus>,
+    ) -> InstructionError {
+        debug!("Error: Script verification failed: {:?}", err);
+        InstructionError::InvalidInstructionData
     }
     #[allow(clippy::needless_pass_by_value)]
     fn map_data_error(err: std::boxed::Box<bincode::ErrorKind>) -> InstructionError {
@@ -238,9 +244,8 @@ impl MoveProcessor {
         let mut data_store = Self::keyed_accounts_to_data_store(&keyed_accounts[GENESIS_INDEX..])?;
 
         let (verified_script, modules) =
-                    // TODO: This function calls `.expect()`, switch to verify_program
-                    static_verify_program(&invoke_info.sender_address, compiled_script, modules)
-                        .expect("verification failure");
+            static_verify_program(&invoke_info.sender_address, compiled_script, modules)
+                .map_err(Self::map_vm_verification_error)?;
         let output = Self::execute(invoke_info, verified_script, modules, &data_store)?;
         for event in output.events() {
             trace!("Event: {:?}", event);
@@ -248,7 +253,9 @@ impl MoveProcessor {
         data_store.apply_write_set(&output.write_set());
 
         // Break data store into a list of address keyed WriteSets
-        let mut write_sets = data_store.into_write_sets();
+        let mut write_sets = data_store
+            .into_write_sets()
+            .map_err(|_| InstructionError::GenericError)?;
 
         // Genesis account holds both mint and stdlib under address 0x0
         let write_set = write_sets