Add code generation issue type

Author: Kaliumhexacyanoferrat

.github/ISSUE_TEMPLATE/code-generation-issue.md

@@ -0,0 +1,24 @@
+---
+name: Code Generation Issue
+about: Report an issue with compiled webservice handlers.
+title: ''
+labels: bug, code-generation
+assignees: ''
+
+---
+
+When using a method with the signature below, the server displays an error page when navigating to the endpoint.
+
+**Example**
+
+```csharp
+// paste the signature of the failing method here (the implementation is not required)
+var app = Inline.Create()
+                .Get(() => 42);
+```
+
+**Additional Information**
+
+- [Anything that might be relevant to reproduce this issue]
+- [e.g. the server of the version]
+- [or what changed so the issue has now occurred]