Not possible to send an optional empty tuple

Fixes #2271

ui/address/contract/methods/form/ContractMethodFieldInputTuple.tsx

@@ -42,6 +42,7 @@ const ContractMethodFieldInputTuple = ({ data, basePath, level, isDisabled, isOp
               basePath={ `${ basePath }:${ index }` }
               level={ level + 1 }
               isDisabled={ isDisabled }
+              isOptional={ isOptional }
             />
           );
         }

ui/address/contract/methods/form/utils.test.ts

@@ -74,4 +74,27 @@ describe('transformFormDataToMethodArgs', () => {
       ],
     ]);
   });
+
+  it('should transform all nested empty arrays to empty arrays', () => {
+    const formData = {
+      '0': '0x1D415D28380ff51A507F7B176ca5F27833F7FffD',
+      '1': '0x1D415D28380ff51A507F7B176ca5F27833F7FffD',
+      '2': '3160',
+      '3': true,
+      // tuple array without elements
+      '4:0:0:0': undefined,
+      '4:0:1:0': undefined,
+      '4:0:1:1': undefined,
+      '4:0:1:2': undefined,
+      '4:0:1:3': undefined,
+    };
+    const result = transformFormDataToMethodArgs(formData);
+    expect(result).toEqual([
+      '0x1D415D28380ff51A507F7B176ca5F27833F7FffD',
+      '0x1D415D28380ff51A507F7B176ca5F27833F7FffD',
+      '3160',
+      true,
+      [],
+    ]);
+  });
 });

ui/address/contract/methods/form/utils.ts

@@ -81,7 +81,9 @@ export function transformFormDataToMethodArgs(formData: ContractMethodFormFields
     _set(result, field.replaceAll(':', '.'), value);
   }
 
-  return filterOutEmptyItems(result);
+  const filteredResult = filterOutEmptyItems(result);
+  const mappedResult = mapEmptyNestedArrays(filteredResult);
+  return mappedResult;
 }
 
 function filterOutEmptyItems(array: Array<unknown>): Array<unknown> {
@@ -90,11 +92,26 @@ function filterOutEmptyItems(array: Array<unknown>): Array<unknown> {
   //        The only optional field is the native coin value, which is safely handled in the form submit handler.
   //    2. When the user adds and removes items from a field array.
   //        In this scenario, empty items need to be filtered out to maintain the correct sequence of arguments.
+  // We don't use isEmptyField() function here because of the second case otherwise it will not keep the correct order of arguments.
   return array
     .map((item) => Array.isArray(item) ? filterOutEmptyItems(item) : item)
     .filter((item) => item !== undefined);
 }
 
+function isEmptyField(field: unknown): boolean {
+  // the empty string is meant that the field was touched but left empty
+  // the undefined is meant that the field was not touched
+  return field === undefined || field === '';
+}
+
+function isEmptyNestedArray(array: Array<unknown>): boolean {
+  return array.flat(Infinity).filter((item) => !isEmptyField(item)).length === 0;
+}
+
+function mapEmptyNestedArrays(array: Array<unknown>): Array<unknown> {
+  return array.map((item) => Array.isArray(item) && isEmptyNestedArray(item) ? [] : item);
+}
+
 export function getFieldLabel(input: ContractAbiItemInput, isRequired?: boolean) {
   const name = input.name || input.internalType || '<unnamed argument>';
   return `${ name } (${ input.type })${ isRequired ? '*' : '' }`;