[eslint-plugin] Add test for invariants

Turning off this flag makes only critical errors throw, so TODO errors will no 
longer be surfaced by the plugin. The previously failing test for unsupported 
syntax is now valid.

compiler/forget/packages/eslint-plugin-react-forget/__tests__/ReactForgetDiagnostics-test.ts

@@ -30,8 +30,6 @@ const tests: ForgetTestCases = {
         }
       `,
     },
-  ],
-  invalid: [
     {
       name: "Unsupported syntax",
       code: normalizeIndent`
@@ -40,8 +38,31 @@ const tests: ForgetTestCases = {
           return y * x;
         }
       `,
+    },
+  ],
+  invalid: [
+    {
+      name: "[Invariant] Defined after use",
+      code: normalizeIndent`
+        function Component(props) {
+          let y = function () {
+            m(x);
+          };
+
+          let x = { a };
+          m(x);
+          return y;
+        }
+      `,
       errors: [
-        "[ReactForget] Todo: (BuildHIR::lowerStatement) Handle var kinds in VariableDeclaration (3:3)",
+        {
+          message:
+            "[ReactForget] Invariant: EnterSSA: Expected identifier to be defined before being used. Identifier x$2 is undefined (7:7)",
+          line: 7,
+          column: 3,
+          endColumn: 17,
+          endLine: 7,
+        },
       ],
     },
   ],

compiler/forget/packages/eslint-plugin-react-forget/src/rules/ReactForgetDiagnostics.ts

@@ -34,7 +34,7 @@ const rule: Rule.RuleModule = {
         Program(prog) {
           try {
             compileProgram(prog, {
-              opts: parsePluginOptions(null), // use defaults for now
+              opts: parsePluginOptions({ panicOnBailout: false }),
               filename: context.filename,
               comments: babelAST.comments ?? [],
             });