Fix block_throw silently returning whole file when token matches without braces

When block_throw=True and the token appeared as a substring on a line
without braces (e.g. block="foo" matching "call_foo();"), found_block
was set but no lines were selected, causing the entire file to be
returned instead of raising ValueError. Check selected_lines instead
of found_block to catch this case.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rnorth

codeinclude/resolver.py

@@ -46,7 +46,7 @@ def select(
 
             delim_count -= line.count("}")
 
-        if block_throw and not found_block:
+        if block_throw and not selected_lines:
             raise ValueError(f"Block {block} not found to inject from {filename}")
 
     if inside_block:
@@ -79,7 +79,7 @@ def select(
             if inside_matching and not first_line_of_block:
                 selected_lines.append(line_number)
 
-        if block_throw and not found_block:
+        if block_throw and not selected_lines:
             raise ValueError(f"Block {inside_block} not found to inject from {filename}")
 
     if from_token and to_token:

tests/codeinclude/test_resolver.py

@@ -46,6 +46,28 @@ def test_block_throw(self):
           result = select(CODE_BLOCK_EXAMPLE, "test_file", inside_block="nonexistent_block", block_throw=True)
 
 
+    def test_block_throw_when_token_matches_but_no_braces(self):
+        """block_throw should raise when a token appears on a line without braces,
+        rather than silently returning the whole file."""
+        text = textwrap.dedent("""
+            void call_foo();
+            int x = 1;
+        """)
+
+        with self.assertRaises(ValueError):
+            select(text, "test_file", block="foo", block_throw=True)
+
+    def test_inside_block_throw_when_token_matches_but_no_braces(self):
+        """inside_block with block_throw should raise when the token appears
+        on a line without braces, rather than silently returning the whole file."""
+        text = textwrap.dedent("""
+            void call_foo();
+            int x = 1;
+        """)
+
+        with self.assertRaises(ValueError):
+            select(text, "test_file", inside_block="foo", block_throw=True)
+
     def test_block_curly_on_same_line(self):
         result = select(
             textwrap.dedent(