fix: custom token validation for non-token addresses

When contract addresses that are not ERC-20 or ERC-721 were input, the token would be allowed to be added and would crash the app.

In addition, when an ERC-20 contract was deployed without a name and symbol, “Invalid ERC-20 address” would appear.

This PR adds error checking from the token detail lookup and reports the error back to the user in the modal. This prevents non-ERC-20/721 contracts from being able to be added to the app and prevents a crash.

src/app/wallet/views/token_list.nim

@@ -1,5 +1,5 @@
 import # nim libs
-  tables, json
+  strformat, tables, json
 
 import # vendor libs
   NimQml
@@ -21,18 +21,24 @@ type
     address: string
 
 const getTokenDetailsTask: Task = proc(argEncoded: string) {.gcsafe, nimcall.} =
-  let 
-    arg = decode[GetTokenDetailsTaskArg](argEncoded)
-    tkn = newErc20Contract(getCurrentNetwork(), arg.address.parseAddress)
-    decimals = tkn.tokenDecimals()
-
-  let output = %* {
-    "address": arg.address,
-    "name": tkn.tokenName(),
-    "symbol": tkn.tokenSymbol(),
-    "decimals": (if decimals == 0: "" else: $decimals)
-  }
-  arg.finish(output)
+  let arg = decode[GetTokenDetailsTaskArg](argEncoded)
+  try:
+    let 
+      tkn = newErc20Contract(getCurrentNetwork(), arg.address.parseAddress)
+      decimals = tkn.tokenDecimals()
+      output = %* {
+        "address": arg.address,
+        "name": tkn.tokenName(),
+        "symbol": tkn.tokenSymbol(),
+        "decimals": (if decimals == 0: "" else: $decimals)
+      }
+    arg.finish(output)
+  except Exception as e:
+    let output = %* {
+      "address": arg.address,
+      "error": fmt"{e.msg}. Is this an ERC-20 or ERC-721 contract?",
+    }
+    arg.finish(output)
 
 proc getTokenDetails[T](self: T, slot: string, address: string) =
   let arg = GetTokenDetailsTaskArg(

ui/app/AppLayouts/Wallet/AddCustomTokenModal.qml

@@ -67,13 +67,17 @@ ModalPopup {
             target: walletModel.customTokenList
             onTokenDetailsWereResolved: {
                 const jsonObj = JSON.parse(tokenDetails)
-                if(jsonObj.name === "" || jsonObj.symbol === "" || jsonObj.decimals === ""){
+                if (jsonObj.error) {
+                    validationError = jsonObj.error
+                    return
+                }
+                if (jsonObj.name === "" && jsonObj.symbol === "" && jsonObj.decimals === "") {
                     //% "Invalid ERC20 address"
                     validationError = qsTrId("invalid-erc20-address")
                     return;
                 }
 
-                if(addressInput.text.toLowerCase() === jsonObj.address.toLowerCase()){
+                if (addressInput.text.toLowerCase() === jsonObj.address.toLowerCase()) {
                     symbolInput.text = jsonObj.symbol;
                     decimalsInput.text = jsonObj.decimals;
                     nameInput.text = jsonObj.name;

ui/shared/Input.qml

@@ -179,7 +179,8 @@ Item {
         font.pixelSize: 12
         height: 16
         color: Style.current.danger
-        width: parent.width
+        width: inputRectangle.width
+        wrapMode: TextEdit.Wrap
     }
 }