fix(codegen): validate sourcemap options (#25860)

## Summary
- require a string sourceText when sourcemaps are enabled
- reject non-string supplied sourceFilename values before map generation
- cover invalid and valid source-map option combinations

packages/codegen/src-js/index.ts

@@ -70,7 +70,15 @@ export function printSync(node: ESTree.Node, options?: Options): CodegenResult {
     options = EMPTY_OPTIONS;
   } else {
     if (options.ts === true) index = 1;
-    if (options.sourcemap === true) index |= 2;
+    if (options.sourcemap === true) {
+      if (typeof options.sourceText !== "string") {
+        throw new TypeError("`sourceText` must be a string when `sourcemap` is true");
+      }
+      if (options.sourceFilename !== undefined && typeof options.sourceFilename !== "string") {
+        throw new TypeError("`sourceFilename` must be a string when supplied");
+      }
+      index |= 2;
+    }
   }
 
   let print = printers[index];

packages/codegen/src-js/print/options.ts

@@ -49,7 +49,7 @@ export interface Options {
   sourcemap?: boolean;
 
   /**
-   * Original source text. Required for source-map mappings.
+   * Original source text. Required when `sourcemap` is `true`.
    */
   sourceText?: string;
 

packages/codegen/test/source-maps.test.ts

@@ -201,6 +201,47 @@ describe("Rust conformance", () => {
   });
 });
 
+describe("source map options", () => {
+  const code = "const value = 1;";
+  const program = parseProgram("options.js", code);
+
+  test.each([
+    ["missing", undefined],
+    ["null", null],
+    ["number", 1],
+  ])("rejects %s sourceText", (_name, sourceText) => {
+    expect(() =>
+      printSync(program, { sourcemap: true, sourceText: sourceText as unknown as string }),
+    ).toThrowError(new TypeError("`sourceText` must be a string when `sourcemap` is true"));
+  });
+
+  test.each([
+    ["null", null],
+    ["number", 1],
+  ])("rejects %s sourceFilename", (_name, sourceFilename) => {
+    expect(() =>
+      printSync(program, {
+        sourcemap: true,
+        sourceText: code,
+        sourceFilename: sourceFilename as unknown as string,
+      }),
+    ).toThrowError(new TypeError("`sourceFilename` must be a string when supplied"));
+  });
+
+  test("accepts valid source map options", () => {
+    expect(
+      printSync(program, {
+        sourcemap: true,
+        sourceText: code,
+        sourceFilename: "options.js",
+      }).map,
+    ).toMatchObject({
+      sources: ["options.js"],
+      sourcesContent: [code],
+    });
+  });
+});
+
 interface Fixture {
   name: string;
   /** Source text, or `null` if the fixture is a cached file which has not been downloaded */