Fix replacer error on patches with empty Runs (#2875)

* Add test to demonstrate empty strings not creating runs

* Fix Run not creating Text child for empty strings

* Simplify TextRun constructor

Since `Run` already has a option for instantiating a `Text` element, we don't need to push children here.

* Add replacer test for empty runs

* Add replacer test for empty runs

* replacer: handle patches with empty runs

* Fix incorrect test name

src/file/paragraph/run/run.ts

@@ -155,7 +155,7 @@ export class Run extends XmlComponent {
 
                 this.root.push(child);
             }
-        } else if (options.text) {
+        } else if (options.text !== undefined) {
             this.root.push(new Text(options.text));
         }
     }

src/file/paragraph/run/text-run.spec.ts

@@ -16,6 +16,14 @@ describe("TextRun", () => {
                 "w:r": [{ "w:t": [{ _attr: { "xml:space": "preserve" } }, "test"] }],
             });
         });
+
+        it("should add empty text into run", () => {
+            run = new TextRun({ text: "" });
+            const f = new Formatter().format(run);
+            expect(f).to.deep.equal({
+                "w:r": [{ "w:t": [{ _attr: { "xml:space": "preserve" } }, ""] }],
+            });
+        });
     });
 
     describe("#referenceFootnote()", () => {

src/file/paragraph/run/text-run.ts

@@ -1,14 +1,7 @@
 import { IRunOptions, Run } from "./run";
-import { Text } from "./run-components/text";
 
 export class TextRun extends Run {
     public constructor(options: IRunOptions | string) {
-        if (typeof options === "string") {
-            super({});
-            this.root.push(new Text(options));
-            return this;
-        }
-
-        super(options);
+        super(typeof options === "string" ? { text: options } : options);
     }
 }

src/patcher/replacer.spec.ts

@@ -77,7 +77,7 @@ export const MOCK_JSON = {
 
 describe("replacer", () => {
     describe("replacer", () => {
-        it("should throw an error if nothing is added", () => {
+        it("should return { didFindOccurrence: false } if nothing is added", () => {
             const { didFindOccurrence } = replacer({
                 json: {
                     elements: [],
@@ -660,5 +660,71 @@ describe("replacer", () => {
             expect(JSON.stringify(element)).to.contain("Lorem ipsum paragraph");
             expect(didFindOccurrence).toBe(true);
         });
+
+        it("should handle empty runs in patches", () => {
+            // cspell:disable
+            const { element, didFindOccurrence } = replacer({
+                json: {
+                    elements: [
+                        {
+                            type: "element",
+                            name: "w:hdr",
+                            elements: [
+                                {
+                                    type: "element",
+                                    name: "w:p",
+                                    elements: [
+                                        {
+                                            type: "element",
+                                            name: "w:r",
+                                            elements: [
+                                                { type: "text", text: "\n                        " },
+                                                {
+                                                    type: "element",
+                                                    name: "w:rPr",
+                                                    elements: [
+                                                        { type: "text", text: "\n                            " },
+                                                        {
+                                                            type: "element",
+                                                            name: "w:rFonts",
+                                                            attributes: { "w:eastAsia": "Times New Roman" },
+                                                        },
+                                                        { type: "text", text: "\n                        " },
+                                                    ],
+                                                },
+                                                { type: "text", text: "\n                        " },
+                                                {
+                                                    type: "element",
+                                                    name: "w:t",
+                                                    elements: [{ type: "text", text: "{{empty}}" }],
+                                                },
+                                                { type: "text", text: "\n                    " },
+                                            ],
+                                        },
+                                    ],
+                                },
+                            ],
+                        },
+                    ],
+                },
+                // cspell:enable
+                patch: {
+                    type: PatchType.PARAGRAPH,
+                    children: [new TextRun({})],
+                },
+                patchText: "{{empty}}",
+                context: {
+                    file: {} as unknown as File,
+                    viewWrapper: {
+                        Relationships: {},
+                    } as unknown as IViewWrapper,
+                    stack: [],
+                },
+                keepOriginalStyles: true,
+            });
+
+            expect(JSON.stringify(element)).not.to.contain("{{empty}}");
+            expect(didFindOccurrence).toBe(true);
+        });
     });
 });

src/patcher/replacer.ts

@@ -74,7 +74,7 @@ export const replacer = ({
 
                     newRunElements = textJson.map((e) => ({
                         ...e,
-                        elements: [...runElementNonTextualElements, ...e.elements!],
+                        elements: [...runElementNonTextualElements, ...(e.elements ?? [])],
                     }));
 
                     patchedRightElement = {