Fix: When LaTeX array environment is used with @{} in column specifie…

…rs browser hangs. (#2274)

* Replaced HTML/XML Numeric Character Reference like ⅈ with Unicode Escape Sequence like \u2148 for consistancy.

* reverted the change to utf8

* &neq; is invalid entity. Changed it to ≠

* prevChild null check added in getVListChildrenAndDepth funciton to prevent browser hanging

src/core/v-box.ts

@@ -58,6 +58,9 @@ function getVListChildrenAndDepth(
   if ('individualShift' in params) {
     const oldChildren = params.individualShift;
     let prevChild = oldChildren[0];
+    if (prevChild == null)
+      return [null, 0];
+
     const children: (VBoxChild | VBoxElementAndShift)[] = [prevChild];
 
     // Add in kerns to the list of params.children to get each element to be

src/formats/atom-to-math-ml.ts

@@ -390,7 +390,7 @@ function scanOperator(stream: MathMLStream, final: number, options) {
 
   const SPECIAL_OPERATORS = {
     '\\ne': '≠',
-    '\\neq': '&neq;',
+    '\\neq': '≠',
     '\\pm': '±',
     '\\times': '×',
     '\\colon': ':',