docs.ada.dev Crate ppag

ppag 2.1.1

We encountered an error during the generation of documentation: 
<ErrorDecl [] hello3evt.adb:45:4-45:7>
<ErrorDecl [] hello3evt.adb:45:8-45:14>
<ErrorDecl [] hello3evt.adb:45:14-45:15>
<ErrorDecl [] hello3evt.adb:46:4-46:8>
<ErrorDecl [] hello3evt.adb:46:9-46:19>
<ErrorDecl [] hello3evt.adb:46:20-46:22>
<ErrorDecl [] hello3evt.adb:46:23-46:29>
<ErrorDecl [] hello3evt.adb:46:30-46:33>
<ErrorDecl [] hello3evt.adb:46:34-46:42>
<ErrorDecl [] hello3evt.adb:46:42-46:43>

raised LANGKIT_SUPPORT.ERRORS.PROPERTY_ERROR : hello3evt.adb:87:33-87:43: dereferencing a null access
ERROR: Command ["gnatdoc4", "-P", "ppag.gpr", "--output-dir", "/home/chouteau/src/github/alire/docs.ada.dev/crate/ppag/2.1.1", "--front-matter", "crate: ppag", "--no-subprojects"] exited with code 1