fix: show problematic file path when encountering malformed JSON5 (#176)

* fix: show problematic file path when encountering malformed JSON5

* Fix missing assert

Author: fwouts

src/__tests__/tsconfig-loader.test.ts

@@ -207,6 +207,20 @@ describe("loadConfig", () => {
     expect(res).toStrictEqual(config);
   });
 
+  it("It should throw an error including the file path when encountering invalid JSON5", () => {
+    expect(() =>
+      loadTsconfig(
+        "/root/dir1/tsconfig.json",
+        (path) => path === "/root/dir1/tsconfig.json",
+        (_) => `{
+            "compilerOptions": {
+          }`
+      )
+    ).toThrowError(
+      "/root/dir1/tsconfig.json is malformed JSON5: invalid end of input at 3:12"
+    );
+  });
+
   it("It should load a config with extends and overwrite all options", () => {
     const firstConfig = {
       extends: "../base-config.json",

src/tsconfig-loader.ts

@@ -125,7 +125,12 @@ export function loadTsconfig(
 
   const configString = readFileSync(configFilePath);
   const cleanedJson = StripBom(configString);
-  const config: Tsconfig = JSON5.parse(cleanedJson);
+  let config: Tsconfig;
+  try {
+    config = JSON5.parse(cleanedJson);
+  } catch (e) {
+    throw new Error(`${configFilePath} is malformed ${e.message}`);
+  }
   let extendedConfig = config.extends;
 
   if (extendedConfig) {