Add missing test

src/cli/test/fx_platform_test.zig

@@ -1522,3 +1522,19 @@ test "run allows warnings without blocking execution" {
     // Should produce output (runs successfully)
     try testing.expect(std.mem.indexOf(u8, run_result.stdout, "Hello, World!") != null);
 }
+
+test "fx platform method inspect on string" {
+    // Tests that calling .inspect() on a Str correctly reports MISSING METHOD
+    // (Str doesn't have an inspect method, unlike custom opaque types)
+    const allocator = testing.allocator;
+
+    const run_result = try runRoc(allocator, "test/fx/test_method_inspect.roc", .{});
+    defer allocator.free(run_result.stdout);
+    defer allocator.free(run_result.stderr);
+
+    // This should fail because Str doesn't have an inspect method
+    try checkFailure(run_result);
+
+    // Should show MISSING METHOD error
+    try testing.expect(std.mem.indexOf(u8, run_result.stderr, "MISSING METHOD") != null);
+}

test_type_error.roc

@@ -0,0 +1,8 @@
+app [main!] { pf: platform "test/fx/platform/main.roc" }
+
+import pf.Stdout
+
+main! = || {
+    x = 42
+    Stdout.line!(x)
+}