[7.x] [ML] Fix job list crashing due to undefined processed records (#71966) (#72112)

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

Author: qn895

x-pack/plugins/ml/public/application/util/string_utils.test.ts

@@ -38,17 +38,17 @@ describe('ML - string utils', () => {
       initial_record_score: 0,
     };
 
-    test('returns correct values without URI encoding', () => {
+    test('should return correct values without URI encoding', () => {
       const result = replaceStringTokens('user=$user$,time=$timestamp$', testRecord, false);
       expect(result).toBe("user=Des O'Connor,time=1454890500000");
     });
 
-    test('returns correct values for missing token without URI encoding', () => {
+    test('should return correct values for missing token without URI encoding', () => {
       const result = replaceStringTokens('user=$username$,time=$timestamp$', testRecord, false);
       expect(result).toBe('user=$username$,time=1454890500000');
     });
 
-    test('returns correct values with URI encoding', () => {
+    test('should return correct values with URI encoding', () => {
       const testString1 = 'https://www.google.co.uk/webhp#q=$testfield1$';
       const testString2 = 'https://www.google.co.uk/webhp#q=$testfield2$';
       const testString3 = 'https://www.google.co.uk/webhp#q=$testfield3$';
@@ -65,15 +65,15 @@ describe('ML - string utils', () => {
       expect(result4).toBe("https://www.google.co.uk/webhp#q=Des%20O'Connor");
     });
 
-    test('returns correct values for missing token with URI encoding', () => {
+    test('should return correct values for missing token with URI encoding', () => {
       const testString = 'https://www.google.co.uk/webhp#q=$username$&time=$timestamp$';
       const result = replaceStringTokens(testString, testRecord, true);
       expect(result).toBe('https://www.google.co.uk/webhp#q=$username$&time=1454890500000');
     });
   });
 
   describe('detectorToString', () => {
-    test('returns the correct descriptions for detectors', () => {
+    test('should return the correct descriptions for detectors', () => {
       const detector1: Detector = {
         function: 'count',
       };
@@ -102,7 +102,7 @@ describe('ML - string utils', () => {
   });
 
   describe('toLocaleString', () => {
-    test('returns correct comma placement for large numbers', () => {
+    test('should return correct comma placement for large numbers', () => {
       expect(toLocaleString(1)).toBe('1');
       expect(toLocaleString(10)).toBe('10');
       expect(toLocaleString(100)).toBe('100');
@@ -114,10 +114,14 @@ describe('ML - string utils', () => {
       expect(toLocaleString(100000000)).toBe('100,000,000');
       expect(toLocaleString(1000000000)).toBe('1,000,000,000');
     });
+    test('should return empty string for undefined or null', () => {
+      expect(toLocaleString(undefined)).toBe('');
+      expect(toLocaleString(null)).toBe('');
+    });
   });
 
   describe('mlEscape', () => {
-    test('returns correct escaping of characters', () => {
+    test('should return correct escaping of characters', () => {
       expect(mlEscape('foo&bar')).toBe('foo&bar');
       expect(mlEscape('foo<bar')).toBe('foo&lt;bar');
       expect(mlEscape('foo>bar')).toBe('foo&gt;bar');
@@ -128,7 +132,7 @@ describe('ML - string utils', () => {
   });
 
   describe('escapeForElasticsearchQuery', () => {
-    test('returns correct escaping of reserved elasticsearch characters', () => {
+    test('should return correct escaping of reserved elasticsearch characters', () => {
       expect(escapeForElasticsearchQuery('foo+bar')).toBe('foo\\+bar');
       expect(escapeForElasticsearchQuery('foo-bar')).toBe('foo\\-bar');
       expect(escapeForElasticsearchQuery('foo=bar')).toBe('foo\\=bar');

x-pack/plugins/ml/public/application/util/string_utils.ts

@@ -90,7 +90,10 @@ function quoteField(field: string): string {
 
 // add commas to large numbers
 // Number.toLocaleString is not supported on safari
-export function toLocaleString(x: number): string {
+export function toLocaleString(x: number | undefined | null): string {
+  if (x === undefined || x === null) {
+    return '';
+  }
   let result = x.toString();
   if (x && typeof x === 'number') {
     const parts = x.toString().split('.');