Explicitly disallow nested verbatim blocks

src/braket/experimental/autoqasm/program/program.py

@@ -480,8 +480,12 @@ def verbatim_block(self) -> None:
         """Sets the program conversion context into a verbatim block context.
 
         Raises:
-            errors.VerbatimBlockNotAllowed: If the target device does not support verbatim blocks.
+            errors.VerbatimBlockNotAllowed: If a verbatim block is not allowed at this point in
+                the program; for example, if the target device does not support verbatim blocks.
         """
+        if self._in_verbatim:
+            raise errors.VerbatimBlockNotAllowed("Verbatim blocks cannot be nested.")
+
         device = self.get_target_device()
         if (
             device

test/unit_tests/braket/experimental/autoqasm/test_pragmas.py

@@ -41,6 +41,17 @@ def program_func() -> None:
     assert program_func().to_ir() == expected
 
 
+def test_nested_verbatim_box() -> None:
+    @aq.main
+    def program_func() -> None:
+        with aq.verbatim():
+            with aq.verbatim():
+                h(0)
+
+    with pytest.raises(errors.VerbatimBlockNotAllowed):
+        program_func()
+
+
 def test_verbatim_box_invalid_target_qubit() -> None:
     @aq.main
     def program_func() -> None: