[llvm] [yaml2obj] Don't use uninitialized Type (PR #123274)

[James Henderson via llvm-commits]

================
@@ -26,8 +26,10 @@ Sections:
   - Name:  decimal
     Type:  1234
 
+## Check that we can handle unknown section and chunk types.
----------------
jh7370 wrote:

Two remaining nits:

1) I'd get rid of the blank line following this comment, as it helps tie the comment better to the associated RUN lines.
2) I noticed that the other test case in this file follows the pattern:
```
# RUN: ...

# CHECK: ...
...

<YAML>
```
whereas this test case has the CHECK and YAML parts the other way. Could you switch them to match the first test case, please?

https://github.com/llvm/llvm-project/pull/123274