fix(capi): yrx_last_error returning empty strings

capi/src/lib.rs

@@ -325,9 +325,11 @@ pub unsafe extern "C" fn yrx_buffer_destroy(buf: *mut YRX_BUFFER) {
 /// the most recent function was successfully.
 #[no_mangle]
 pub unsafe extern "C" fn yrx_last_error() -> *const c_char {
-    if let Some(last_error) = LAST_ERROR.with(|_| None::<CString>) {
-        last_error.as_ptr()
-    } else {
-        std::ptr::null()
-    }
+    LAST_ERROR.with_borrow(|last_error| {
+        if let Some(last_error) = last_error {
+            last_error.as_ptr()
+        } else {
+            std::ptr::null()
+        }
+    })
 }

go/compiler_test.go

@@ -71,11 +71,18 @@ func TestVariables(t *testing.T) {
 	assert.Len(t, matchingRules, 1)
 
 	err := c.DefineGlobal("var", struct{}{})
-	assert.Errorf(t, err, "variable `var` has unsupported type: struct{}")
+	assert.EqualError(t, err, "variable `var` has unsupported type: struct {}")
 }
 
 func TestError(t *testing.T) {
 	c := NewCompiler()
 	err := c.AddSource("rule test { condition: foo }")
-	assert.Error(t, err)
+	assert.EqualError(t, err, `error: unknown identifier `+"`foo`"+`
+   ╭─[line:1:24]
+   │
+ 1 │ rule test { condition: foo }
+   │                        ─┬─  
+   │                         ╰─── this identifier has not been declared
+───╯
+`)
 }