refactor: Improve parseMetamaskError and add stories (#272)

core/src/helpers/parseMetamaskError.ts

@@ -1,15 +1,44 @@
 import truncateText from './truncateText';
 
-const parseMetamaskError = function (errorMessage = ''): string {
-    const jsonFirstIndex = errorMessage.indexOf('{');
-    const jsonLastIndex = errorMessage.lastIndexOf('}');
-    try {
-        const jsonString = errorMessage.substring(jsonFirstIndex, jsonLastIndex + 1);
-        const metamaskError = JSON.parse(jsonString);
-        return truncateText(metamaskError?.value?.data?.message || 'unknown');
-    } catch {
-        return truncateText(errorMessage || 'unknown');
+const UNKNOWN_ERROR_TEXT = 'unknown error';
+
+const removeSpecialCharacters = function (text = '') {
+    return text.replace(/['\{\}\\"]/gm, '').replace(/\[.+\]/gm, '');
+};
+
+const getErrorDetails = function (errorMessage = '') {
+    // Get useful content between `"message":"` and `"`
+    const START_SYMBOLS = '"message":"';
+    const STOP_SYMBOLS = '"';
+    const jsonFirstIndex = errorMessage.indexOf(START_SYMBOLS);
+    if (jsonFirstIndex === -1) {
+        return '';
+    }
+    const messageStartIndex = jsonFirstIndex + START_SYMBOLS.length;
+    const messageStopIndex = errorMessage.indexOf(STOP_SYMBOLS, messageStartIndex);
+    const extractedContent = errorMessage.substring(messageStartIndex, messageStopIndex);
+    return removeSpecialCharacters(extractedContent).trim();
+};
+
+const getErrorTitle = function (errorMessage = '') {
+    // Get useful content before code starts
+    const jsonStartIndex = errorMessage.search(/[\(\{]/gm);
+    if (jsonStartIndex === -1) {
+        return '';
+    }
+    return errorMessage.substring(0, jsonStartIndex).trim();
+};
+
+const parseMetamaskError = function (errorMessage = ''): unknown {
+    const errorTitle = getErrorTitle(errorMessage);
+    if (!errorTitle) {
+        return truncateText(errorMessage || UNKNOWN_ERROR_TEXT);
+    }
+    const errorDetails = getErrorDetails(errorMessage);
+    if (!errorDetails) {
+        return errorTitle;
     }
+    return `${errorDetails} (${errorTitle})`;
 };
 
 export default parseMetamaskError;