1 files changed, 4 insertions, 3 deletions
diff --git a/extension/background/emscriptif.js b/extension/background/emscriptif.js
index ee864c60d..a4e50b89e 100644
--- a/extension/background/emscriptif.js
+++ b/extension/background/emscriptif.js
@@ -127,7 +127,8 @@ class Amount extends ArenaObject {
      * Perform saturating subtraction on amounts.
      */
     sub(a) {
-        let res = emsc.amount_subtract(this.nativePtr, a.nativePtr, this.nativePtr);
+        // this = this - a
+        let res = emsc.amount_subtract(this.nativePtr, this.nativePtr, a.nativePtr);
         if (res == 0) {
             // Underflow
             return false;
@@ -135,7 +136,7 @@ class Amount extends ArenaObject {
         if (res > 0) {
             return true;
         }
-        throw "Incompatible currencies";
+        throw Error("Incompatible currencies");
     }
     cmp(a) {
         return emsc.amount_cmp(this.nativePtr, a.nativePtr);
@@ -256,7 +257,7 @@ class SignatureStruct {
             let name = f[0];
             let member = this.members[name];
             if (!member) {
-                throw { error: "Member not set", key: name };
+                throw Error(format("Member {0} not set", name));
             }
             totalSize += this.members[name].size();
         }