fix(jest-jasmine2): handle case when stack is not string

Author: snitin315

packages/jest-jasmine2/src/__tests__/__snapshots__/expectationResultFactory.test.ts.snap

@@ -1,5 +1,11 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`expectationResultFactory returns the result if failed (with \`error.stack\` not as a string). 1`] = `
+"thrown: Object {
+  \\"stack\\": Array [],
+}"
+`;
+
 exports[`expectationResultFactory returns the result if passed. 1`] = `
 Object {
   "error": undefined,

packages/jest-jasmine2/src/__tests__/expectationResultFactory.test.ts

@@ -78,4 +78,16 @@ describe('expectationResultFactory', () => {
     const result = expectationResultFactory(options);
     expect(result.message).toEqual('Expected `Pass`, received `Fail`.');
   });
+
+  it('returns the result if failed (with `error.stack` not as a string).', () => {
+    const options = {
+      actual: 'Fail',
+      error: {stack: []},
+      expected: 'Pass',
+      matcherName: 'testMatcher',
+      passed: false,
+    };
+    const result = expectationResultFactory(options);
+    expect(result.message).toMatchSnapshot();
+  });
 });

packages/jest-jasmine2/src/reporter.ts

@@ -113,15 +113,19 @@ export default class Jasmine2Reporter implements Reporter {
     return this._resultsPromise;
   }
 
-  private _addMissingMessageToStack(stack: string, message?: string) {
+  private _addMissingMessageToStack(stack: unknown, message?: string) {
     // Some errors (e.g. Angular injection error) don't prepend error.message
     // to stack, instead the first line of the stack is just plain 'Error'
     const ERROR_REGEX = /^Error:?\s*\n/;
 
-    if (stack && message && !stack.includes(message)) {
-      return message + stack.replace(ERROR_REGEX, '\n');
+    if (typeof stack === 'string') {
+      if (stack && message && !stack.includes(message)) {
+        return message + stack.replace(ERROR_REGEX, '\n');
+      }
+      return stack;
+    } else {
+      return `${stack}`;
     }
-    return stack;
   }
 
   private _extractSpecResults(