Fix bug scripts in Mitmweb (#6668)

#### Description

This PR should fix issue: #6002 

#### Checklist

 - [x] I have updated tests where applicable.
 - [ ] I have added an entry to the CHANGELOG.

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

web/src/js/__tests__/components/Modal/OptionSpec.tsx

@@ -97,6 +97,6 @@ describe("StringOption Component", () => {
     it("should handle onChange", () => {
         let mockEvent = { target: { value: "a\nb\nc\n" } };
         tree.props.onChange(mockEvent);
-        expect(onChangeFn).toBeCalledWith(["a", "b", "c", ""]);
+        expect(onChangeFn).toBeCalledWith(["a", "b", "c"]);
     });
 });

web/src/js/components/Modal/Option.jsx

@@ -99,11 +99,26 @@ StringSequenceOption.propTypes = {
 
 function StringSequenceOption({ value, onChange, ...props }) {
     const height = Math.max(value.length, 1);
+
+    const [textAreaValue, setTextAreaValue] = React.useState(value.join("\n"));
+
+    const handleChange = (e) => {
+        const newValue = e.target.value;
+        setTextAreaValue(newValue); //save in the state the current input value
+        onChange(
+            //we send to the backend only the strings that are not empty
+            newValue
+                .split("\n")
+                .map((line) => line.trim())
+                .filter((line) => line !== "")
+        );
+    };
+
     return (
         <textarea
             rows={height}
-            value={value.join("\n")}
-            onChange={(e) => onChange(e.target.value.split("\n"))}
+            value={textAreaValue}
+            onChange={handleChange}
             {...props}
         />
     );

web/src/js/ducks/options.ts

@@ -34,7 +34,9 @@ export default function reducer(state = defaultState, action): OptionsState {
 
 export async function pureSendUpdate(option: Option, value, dispatch) {
     try {
-        const response = await fetchApi.put("/options", { [option]: value });
+        const response = await fetchApi.put("/options", {
+            [option]: value,
+        });
         if (response.status === 200) {
             dispatch(optionsEditorActions.updateSuccess(option));
         } else {