Ensure errors in ACE NRJavaScript mode are on valid lines

In the case of an "Unmatched {" error, it flags the { on
the line we wrap the user's code in. That doesn't help the
user.

This fix moves such an error to the first valid { in the file.

It handles ignoring { in comments or strings. It fails to ignore
{ inside regex. But that's an edge case on top of an edge case.

packages/node_modules/@node-red/editor-client/src/ace/mode/nrjavascript_worker.js

@@ -128,6 +128,8 @@ oop.inherits(NRJavaScriptWorker, Mirror);
         if (!value)
             return this.sender.emit("annotate", []);
 
+        var originalValue = value;
+
         // [Node-RED] wrap the code in a function
         value = "async function __nodered__(msg) {\n"+value+"\n}";
 
@@ -147,6 +149,7 @@ oop.inherits(NRJavaScriptWorker, Mirror);
                 continue;
             var raw = error.raw;
             var type = "warning";
+            var line = error.line - 2;
 
             if (raw == "Missing semicolon.") {
                 var str = error.evidence.substr(error.character);
@@ -175,9 +178,62 @@ oop.inherits(NRJavaScriptWorker, Mirror);
                 type = "info";
             }
 
+            if (raw === "Unmatched '{a}'." && line === -1) {
+                // This is an unmatched { error. It has incorrectly matched it
+                // against the { in the added line. Need to find the next valid {
+                // This code scans through the original code looking for the first '{'
+                // that is not in a comment or string.
+                // It will incorrectly find a '{' if it is inside a regex... but
+                // at least the error will be shown somwhere. There are only
+                // so many hours in the day to fix every tiny edge case of an
+                // edge case.
+                var inSingleComment = false;
+                var inMultiComment = false;
+                var inString = false;
+                var stringQ;
+                var lineNumber = 0;
+                for (var pos = 0;pos<originalValue.length;pos++) {
+                    var c = originalValue[pos];
+                    if (c === "\\") {
+                        pos++;
+                    } else if (inSingleComment) {
+                        if (c === "\n") {
+                            lineNumber++;
+                            inSingleComment = false;
+                        }
+                    } else if (inMultiComment) {
+                        if (c === "*" && originalValue[pos+1] === "/") {
+                            pos++;
+                            inMultiComment = false;
+                        } else if (c === "\n") {
+                            lineNumber++;
+                        }
+                    } else if (inString) {
+                        if (c === stringQ) {
+                            inString = false;
+                        }
+                    } else if (c === "'" || c === "\"") {
+                        inString = true;
+                        stringQ = c;
+                    } else if (c === "/") {
+                        if (originalValue[pos+1] === "/") {
+                            inSingleComment = true;
+                        } else if (originalValue[pos+1] === "*") {
+                            inMultiComment = true;
+                        }
+                    } else if (c === "\n") {
+                        lineNumber++;
+                    } else if (c === "{") {
+                        // found it!
+                        break;
+                    }
+                }
+                line = lineNumber;
+            }
+
             errors.push({
                 // [Node-RED] offset the row for the added line
-                row: error.line-2,
+                row: Math.max(0,line),
                 column: error.character-1,
                 text: error.reason,
                 type: type,