rpc: refactor app code to use getters with default values

diff --git a/main/assets.c b/main/assets.c
index 4f49408..f16fe2c 100644
--- a/main/assets.c
+++ b/main/assets.c
@@ -169,9 +169,7 @@ bool assets_get_allocate(const char* field, const CborValue* value, asset_info_t
             }
 
             // "precision" field is optional in the asset contract and defaults to 0
-            size_t precision = 0;
-            IGNORE_RESULT(rpc_get_sizet("precision", &contract, &precision));
-            asset->precision = precision;
+            asset->precision = rpc_get_sizet_or("precision", &contract, 0);
         }
 
         CborError err = cbor_value_advance(&arrayItem);
diff --git a/main/process/auth_user.c b/main/process/auth_user.c
index 2cdc7d5..6f517fe 100644
--- a/main/process/auth_user.c
+++ b/main/process/auth_user.c
@@ -359,8 +359,8 @@ void auth_user_process(void* process_ptr)
     }
 
     // Optional flag to suppress user confirmation of any pin change
-    bool suppress_pin_change_confirmation = false;
-    rpc_get_boolean("suppress_pin_change_confirmation", &params, &suppress_pin_change_confirmation);
+    const bool suppress_pin_change_confirmation
+        = rpc_get_boolean_or("suppress_pin_change_confirmation", &params, false);
 
     // We have five cases:
     // 1. Temporary - has a temporary keys in memory
diff --git a/main/process/debug_set_mnemonic.c b/main/process/debug_set_mnemonic.c
index e272a8c..bea2a4f 100644
--- a/main/process/debug_set_mnemonic.c
+++ b/main/process/debug_set_mnemonic.c
@@ -36,7 +36,6 @@ void debug_set_mnemonic_process(void* process_ptr)
     char passphrase[PASSPHRASE_MAX_LEN + 1];
     SENSITIVE_PUSH(passphrase, sizeof(passphrase));
     const char* p_passphrase = NULL;
-    bool temporary_wallet = false;
     const uint8_t* seed = NULL;
     size_t written = 0;
 
@@ -44,7 +43,7 @@ void debug_set_mnemonic_process(void* process_ptr)
     SENSITIVE_PUSH(&keydata, sizeof(keydata));
 
     // Get field which can be set to test 'temporary restore' wallet
-    rpc_get_boolean("temporary_wallet", &params, &temporary_wallet);
+    bool temporary_wallet = rpc_get_boolean_or("temporary_wallet", &params, false);
 
     // Slightly hacky, can accept a seed or a mnemonic
     if (rpc_has_field_data("seed", &params)) {
diff --git a/main/process/get_receive_address.c b/main/process/get_receive_address.c
index b56d3f4..9d4c57b 100644
--- a/main/process/get_receive_address.c
+++ b/main/process/get_receive_address.c
@@ -47,8 +47,8 @@ void get_receive_address_process(void* process_ptr)
     const uint8_t* p_master_blinding_key = NULL;
     size_t master_blinding_key_len = 0;
 
-    bool confidential = isLiquid; // default to confidential addresses for liquid
-    rpc_get_boolean("confidential", &params, &confidential);
+    // Defaults to confidential addresses for liquid
+    const bool confidential = rpc_get_boolean_or("confidential", &params, isLiquid);
     if (confidential && !isLiquid) {
         jade_process_reject_message(
             process, CBOR_RPC_BAD_PARAMETERS, "Confidential addresses only apply to liquid networks");
@@ -110,8 +110,8 @@ void get_receive_address_process(void* process_ptr)
         }
 
         // The path is given in two parts - optional (change) branch and mandatory index pointer
-        size_t branch = 0, pointer = 0;
-        rpc_get_sizet("branch", &params, &branch); // optional
+        const size_t branch = rpc_get_sizet_or("branch", &params, 0); // optional
+        size_t pointer = 0;
         if (!rpc_get_sizet("pointer", &params, &pointer)) {
             jade_process_reject_message(
                 process, CBOR_RPC_BAD_PARAMETERS, "Failed to extract path elements from parameters");
@@ -163,8 +163,7 @@ void get_receive_address_process(void* process_ptr)
             rpc_get_string("recovery_xpub", sizeof(xpubrecovery), &params, xpubrecovery, &written);
 
             // Optional 'blocks' for csv outputs
-            size_t csv_blocks = 0;
-            rpc_get_sizet("csv_blocks", &params, &csv_blocks);
+            const size_t csv_blocks = rpc_get_sizet_or("csv_blocks", &params, 0);
 
             if (csv_blocks && !network_is_known_csv_blocks(network_id, csv_blocks)) {
                 const int ret
diff --git a/main/process/ota_util.c b/main/process/ota_util.c
index 7dc91f4..eaca1b2 100644
--- a/main/process/ota_util.c
+++ b/main/process/ota_util.c
@@ -216,8 +216,7 @@ jade_ota_ctx_t* ota_init(jade_process_t* process, const bool is_delta)
     }
 
     // Optional field indicating preference for rich reply data
-    bool extended_replies = false;
-    rpc_get_boolean("extended_replies", &params, &extended_replies);
+    const bool extended_replies = rpc_get_boolean_or("extended_replies", &params, false);
 
     // Can accept either uploaded file data hash (legacy) or hash of the full/final firmware image (preferred)
     uint8_t expected_hash[SHA256_LEN];
diff --git a/main/process/register_multisig.c b/main/process/register_multisig.c
index eff0d77..3f8efd2 100644
--- a/main/process/register_multisig.c
+++ b/main/process/register_multisig.c
@@ -711,8 +711,7 @@ void register_multisig_process(void* process_ptr)
     }
 
     // Threshold
-    written = 0;
-    rpc_get_sizet("threshold", &descriptor, &written);
+    written = rpc_get_sizet_or("threshold", &descriptor, 0);
     if (written == 0 || written > MAX_ALLOWED_SIGNERS) {
         jade_process_reject_message(process, CBOR_RPC_BAD_PARAMETERS, "Invalid multisig threshold value");
         goto cleanup;
diff --git a/main/process/sign_tx.c b/main/process/sign_tx.c
index 2e1e561..38761f8 100644
--- a/main/process/sign_tx.c
+++ b/main/process/sign_tx.c
@@ -133,10 +133,8 @@ static bool params_signing_outputs(jade_process_t* process, const CborValue* par
 
             // For backward-compatibility reasons we assume all populated items
             // are change unless told otherwise (ie. explicit is_change: false)
-            bool is_change = true;
-            rpc_get_boolean("is_change", &arrayItem, &is_change);
+            bool is_change = rpc_get_boolean_or("is_change", &arrayItem, true);
 
-            size_t csv_blocks = 0;
             size_t script_len = 0;
             uint8_t script[WALLY_SCRIPTPUBKEY_P2WSH_LEN]; // Sufficient
             size_t written = 0;
@@ -190,8 +188,8 @@ static bool params_signing_outputs(jade_process_t* process, const CborValue* par
                 }
 
                 // The path is given in two parts - optional (change) branch and mandatory index pointer
-                size_t branch = 0, pointer = 0;
-                rpc_get_sizet("branch", &arrayItem, &branch); // optional
+                const size_t branch = rpc_get_sizet_or("branch", &arrayItem, 0); // optional
+                size_t pointer = 0;
                 if (!rpc_get_sizet("pointer", &arrayItem, &pointer)) {
                     errmsg = "Failed to extract path elements from parameters";
                     goto cleanup;
@@ -240,8 +238,8 @@ static bool params_signing_outputs(jade_process_t* process, const CborValue* par
                         is_change = false;
                     }
 
-                    // Optional 'blocks' for csv outputs
-                    rpc_get_sizet("csv_blocks", &arrayItem, &csv_blocks);
+                    // Optional 'blocks' for csv outputs, defaults to 0
+                    const size_t csv_blocks = rpc_get_sizet_or("csv_blocks", &arrayItem, 0);
 
                     // If number of csv blocks unexpected show a warning message and ask the user to confirm
                     if (csv_blocks && !network_is_known_csv_blocks(network_id, csv_blocks)) {
@@ -452,8 +450,7 @@ static void sign_tx_impl(jade_process_t* process, const bool for_liquid)
 
     // Whether to use Anti-Exfil signatures and message flow
     // Optional flag, defaults to false
-    bool use_ae_signatures = false;
-    rpc_get_boolean("use_ae_signatures", &params, &use_ae_signatures);
+    const bool use_ae_signatures = rpc_get_boolean_or("use_ae_signatures", &params, false);
 
     commitment_t* commitments = NULL;
     // Liquid: Copy trusted commitment data so we can free the message
@@ -648,8 +645,7 @@ static void sign_tx_impl(jade_process_t* process, const bool for_liquid)
             }
         } else if (!for_liquid) {
             // Bitcoin: May still need witness flag
-            bool is_witness = false;
-            rpc_get_boolean("is_witness", &params, &is_witness);
+            const bool is_witness = rpc_get_boolean_or("is_witness", &params, false);
             input_data->sig_type = is_witness ? WALLY_SIGTYPE_SW_V0 : WALLY_SIGTYPE_PRE_SW;
             input_data->sighash = WALLY_SIGHASH_ALL;
         }
diff --git a/main/process/update_pinserver.c b/main/process/update_pinserver.c
index afb334b..e588c17 100644
--- a/main/process/update_pinserver.c
+++ b/main/process/update_pinserver.c
@@ -87,9 +87,8 @@ int update_pinserver(const CborValue* const params, const char** errmsg)
 
     int retval = CBOR_RPC_BAD_PARAMETERS;
 
-    // 1. update or erase the pinserver details
-    bool reset_details = false;
-    rpc_get_boolean("reset_details", params, &reset_details);
+    // 1. update or erase the pinserver details (defaults to false)
+    const bool reset_details = rpc_get_boolean_or("reset_details", params, false);
 
     size_t urlA_len = 0, urlB_len = 0;
     rpc_get_string("urlA", sizeof(urlA), params, urlA, &urlA_len);
@@ -176,9 +175,8 @@ int update_pinserver(const CborValue* const params, const char** errmsg)
         }
     }
 
-    // 2. update or erase the certificate
-    bool reset_certificate = false;
-    rpc_get_boolean("reset_certificate", params, &reset_certificate);
+    // 2. update or erase the certificate (defaults to false)
+    const bool reset_certificate = rpc_get_boolean_or("reset_certificate", params, false);
     const bool set_certificate = rpc_has_field_data("certificate", params);
 
     if (set_certificate && reset_certificate) {